Spectroscopic Color Measurement Device and Method for Setting Conversion Rule

ABSTRACT

Spectrocolorimetric device includes a light source, a light-receiving unit, a calculation unit, a storage unit, an acquisition unit, and a conversion unit. The light-receiving unit spectroscopically disperses reflected light generated on a surface and measures a spectroscopic spectrum relating to the reflected light. The calculation unit calculates a first spectral reflectance from the spectroscopic spectrum. The storage unit stores relationship information indicating a relationship between a reflectance and a reflectance difference for each wavelength. The acquisition unit acquires reflectance difference for each wavelength between the first spectral reflectance acquired using the spectrocolorimetric device and a second spectral reflectance acquired using a destination-of-conversion spectrocolorimetric device on the basis of the first spectral reflectance and the relationship information. The conversion unit converts the first spectral reflectance into the second spectral reflectance by adding or subtracting the reflectance difference for each wavelength acquired by the acquisition unit to or from the first spectral reflectance.

TECHNICAL FIELD

The present invention relates to a spectrocolorimetric device and aconversion rule setting method for setting a rule for converting ameasurement value acquired by a spectrocolorimetric device into aspectral reflectance obtainable by other spectrocolorimetric devices.

BACKGROUND ART

In recent years, in order to manage finishing of a surface color of anobject, a spectrocolorimetric device for measuring a spectralreflectance on a surface of the object is used (for example, PatentLiteratures 1 to 3, or the like). In the spectrocolorimetric device, forexample, by using measurement values relating to black chromacity andwhite chromacity obtained by measurement of two standard colors of blackand white, a measurement value relating to the spectral reflectance ofthe object can be calibrated (for example, Patent Literature 1, or thelike).

With respect to such spectrocolorimetric devices, for example, aplurality of spectrocolorimetric devices are used in parallel in afactory or the like, and some of the spectrocolorimetric devices arereplaced with new spectrocolorimetric devices, so that a usage situationin which plural types of the spectrocolorimetric devices can coexist canbe assumed. As a mode of replacing the spectrocolorimetric devices, forexample, there is a mode in which a spectrocolorimetric device that hasbeen used up to now is replaced with a succeeding model of thespectrocolorimetric device.

In this usage situation, if measurement values of two standard colors ofblack and white are used and the measurement values relating to theobject are calibrated, with respect to objects close to black and white,even though the same object is measured by different spectrocolorimetricdevices, similar spectral reflectances can be obtained. On the otherhand, since calibration methods relating to the optical system andspectral sensitivity are different between different models or betweendevices manufactured by different manufacturers, if objects of colorsdifferent from black and white are measured by differentspectrocolorimetric devices, different spectral reflectances can beacquired for different spectrocolorimetric devices.

Therefore, a method of converting a spectral reflectance R_(m)(i)obtained by measurement of a certain object with a spectrocolorimetricdevice m to a spectral reflectance R_(t)(i) obtained by measurement ofthe same object with another spectrocolorimetric device t byMathematical Formula (1) is proposed (for example, Non Patent Literature1 or the like). In Mathematical Formula (1), λ denotes a wavelength, andA(i), B(i), C(i), D(i), and E(i) denote coefficients of the first tofifth terms of the right hand side with respect to each i-th wavelengthλ.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 1} \right\rbrack} & \; \\{{R_{t}(i)} = {{A(i)} + {{B(i)} \cdot {R_{m}(i)}} + {{C(i)} \cdot \frac{{dR}_{m}(i)}{d\; \lambda}} + {{D(i)} \cdot \frac{d^{2}{R_{m}(i)}}{d\; \lambda^{2}}} + {{E(i)} \cdot {R_{m}(i)} \cdot \left( {100 - {R_{m}(i)}} \right)}}} & (1)\end{matrix}$

In this method, the spectral reflectances acquired by actually measuringa plurality of calibration samples with the spectrocolorimetric device mand the spectrocolorimetric device t are applied to Mathematical Formula(1), so that the coefficients A(i), B(i), C(i), D(i), and E(i) ofMathematical Formula (1) are obtained. By using Mathematical Formula (1)to which the obtained coefficients A(i), B(i), C(i), D(i), and E(i) areapplied, the spectral reflectance R_(t)(i) which is to be acquired bymeasurement using the spectrocolorimetric device t can be calculatedfrom the spectral reflectance R_(m)(i) which can be acquired bymeasurement for any object using the spectrocolorimetric device m.

CITATION LIST Patent Literature

Patent Literature 1: JP 61-292026 A

Patent Literature 2: JP 61-292043 A

Patent Literature 3: JP 62-289736 A

Non Patent Literature

Non Patent Literature 1: A. Ingleson and M. H. Brill, “Methods ofSelecting a Small Reflectance Set as a Transfer Standard for CorrectingSpectrophotometers”, Color Res. Appl. 31 (2006), 13-17.

SUMMARY OF INVENTION Technical Problem

On the other hand, for example, the spectral reflectance is illustratedby a two-dimensional graph where the horizontal axis denotes awavelength in reflected light from an object and the vertical axisdenotes a reflectance according to an intensity (or optical energy) ofthe reflected light from the object. For this reason, a deviation in thespectral reflectance between the different spectrocolorimetric devicesmay occur in two axial directions of the horizontal axial directionrelating to the wavelength and the vertical axial direction relating tothe optical energy. Referring to Mathematical Formula (1), the problemof linearity where the relationship between the intensity of thereflected light from the object and the measurement value for eachlight-receiving element of the spectrocolorimetric device is deviatedfrom a proportional relationship may cause an error in the coefficientE(i) of the fifth term of the right hand side. In addition, thedeviation relating to the wavelength of the reflected light received byeach light-receiving element of the spectrocolorimetric device causes anerror in the coefficient C(i) of the third term on the right hand sideof Mathematical Formula (1). Further, a deviation in the full width athalf maximum of the spectral sensitivity of each light-receiving elementcorresponding to each wavelength of the spectrocolorimetric device cancause an error in the coefficient D(i) of the fourth term on the righthand side of Mathematical Formula (1).

Herein, the coefficients A(i) to E(i) employ different values fordifferent wavelengths λ(i). For this reason, for each wavelength λ(i),when spectral reflectances of five or more types of calibration samplesof which a spectral reflectance R_(m)(i) and a first derivative(dR_(m)(i)/dλ) and a second derivative (d²R_(m)(i)/dλ²) of the spectralreflectance R_(m)(i) have values other than zero are actually measured,five coefficients A(i) to E(i) can be obtained for each wavelength λ(i).

For example, when a calibration sample of which the spectral reflectanceR_(m)(i) has a slope with respect to the change of the wavelength λ(i)for each wavelength λ(i) (referred to as a detection wavelength) atwhich the intensity of the reflected light is detected in thespectrocolorimetric device is used, the third term on the right handside including the first derivative (d²R_(m)(i)/dλ²) of the spectralreflectance R_(m)(i) in Mathematical Formula (1) has a value differentfrom zero. In addition, for example, when a calibration sample of whichslope of the spectral reflectance R_(m)(i) is changed with respect tothe change of the detection wavelength λ(i) is used for each detectionwavelength λ(i) of the spectrocolorimetric device, the fourth term onthe right hand side including the second derivative (d²R_(m)(i)/dλ²) ofthe spectral reflectance R_(m)(i) in Mathematical Formula (1) has avalue different from zero.

Therefore, if a calibration sample of which the spectral reflectanceR_(m)(i), the slope of the spectral reflectance R_(m)(i), and a changein the slope of the spectral reflectance R_(m)(i) are large is used foreach detection wavelength λ(i), the coefficients A(i) to D(i) can beobtained at a good accuracy. In addition, the fifth term on the righthand side is a quadratic function which becomes the minimum at thespectral reflectance R_(m)(i) of 0% and 100% and becomes the maximum atthe spectral reflectance R_(m)(i) of 50%. For this reason, when aplurality of calibration samples exhibiting a plurality of spectralreflectances R_(m)(i) ranging from 0% to 100% are employed for eachdetection wavelength λ(i), the coefficient E(i) can be obtained at agood accuracy.

However, in a calibration sample of which the slope of the spectralreflectance R_(m)(i) at a certain detection wavelength λ(i) is large,the slope of the spectral reflectance R_(m)(i) is likely to be decreasedat a different detection wavelength λ(i). For this reason, for eachdetection wavelength λ(i), the optimum calibration sample for obtainingthe coefficients A(i) to E(i) will be different. Therefore, in order toobtain the coefficients A(i) to E(i) for each wavelength λ(i), a verylarge number of calibration samples are required. In addition, dependingon a method of selecting the calibration sample, the robustness withrespect to the calculation of the spectral reflectance R_(t)(i) usingMathematical Formula (1) is different. Namely, when an error relating tomeasurement according to the method of selecting the calibration sampleis added to one or more terms on the right hand side of MathematicalFormula (1), the spectral reflectance R_(t)(i) calculated usingMathematical Formula (1) is likely to have an error.

In addition, in the spectrocolorimetric device, the measurement valuerelating to the spectral reflectance R_(m)(i) is output at a presetpredetermined wavelength interval such as an interval of 10 nm or thelike. For this reason, in the actual calculation, the first derivative(dR_(m)(i)/dλ) of the spectral reflectance R_(m)(i) at the detectionwavelength λ(i) is not a value (also referred to as a differentialvalue) of the differential of the spectral reflectance R_(m)(i) but avalue (also referred to as a difference value) of the difference of thespectral reflectance R_(m)(i). As a result, the error due to thedifference between the differential value and the difference valuecauses an error between the spectral reflectance R_(t)(i) relating tothe spectrocolorimetric device t obtained by the conversion usingMathematical Formula (1) from the spectral reflectance R_(m)(i) obtainedby the spectrocolorimetric device m and the spectral reflectanceR_(t)(i) obtained by actual measurement using the spectrocolorimetricdevice t.

In this manner, in order to realize the conversion from the spectralreflectance R_(m)(i) to the spectral reflectance R_(t)(i) by usingMathematical Formula (1), a large number of calibration samples arefirst required. In addition, it takes a long time to perform themeasurement using a large number of the calibration samples.Furthermore, it is not easy to secure a conversion accuracy (robustness)depending on a method of selecting the calibration sample. Namely,complicated manipulations or operations are required for setting a rule(also referred to as a conversion rule) for converting the spectralreflectance R_(m)(i) into the spectral reflectance R_(t)(i), and thus,it is not easy to set the conversion rule at a high accuracy.

These problems are not limited between spectrocolorimetric devices ofdifferent manufacturers or between different models ofspectrocolorimetric devices, but these problems may also occur betweendifferent spectrocolorimetric devices of the same model, and thus, theseproblems may generally occur between different spectrocolorimetricdevices.

In view of the above problems, the present invention is to provide atechnique by which a highly-accurate conversion rule of measurementvalues between different spectrocolorimetric devices can be easily set.

Solution to Problem

In order to solve the above problem, a spectrocolorimetric deviceaccording to one aspect includes a light source, a light-receiving unit,a calculation unit, a storage unit, an acquisition unit, and aconversion unit. Herein, the light-receiving unit spectroscopicallydisperses reflected light generated on a surface of an object accordingto irradiation of the object with illumination light emitted from thelight source and measures a spectroscopic spectrum relating to thereflected light. The calculation unit calculates a first spectralreflectance from the spectroscopic spectrum. The storage unit storesrelationship information indicating a relationship between a reflectanceand a reflectance difference as a deviation component of reflectance foreach wavelength. The acquisition unit acquires reflectance differencefor each wavelength between the first spectral reflectance acquired bymeasurement using the spectrocolorimetric device and a second spectralreflectance that can be acquired by measurement using adestination-of-conversion spectrocolorimetric device different from thespectrocolorimetric device on the basis of the first spectralreflectance and the relationship information. The conversion unitconverts the first spectral reflectance into the second spectralreflectance by adding or subtracting the reflectance difference for eachwavelength acquired by the acquisition unit to or from the firstspectral reflectance.

A conversion rule setting method according to another aspect includessteps (a) to (c). Herein, in step (a), in a first spectrocolorimetricdevice and a second spectrocolorimetric device, a spectral reflectancefor each sample among a plurality of different samples of whichreflectance is included within a width of a preset predetermined valuerange in at least a portion of a wavelength range in a to-be-measuredwavelength range is measured. In the step (b), in an arithmetic unit, arelationship between a reflectance for each wavelength between aplurality of first spectral reflectances acquired by measurement on theplurality of samples using the first spectrocolorimetric device and aplurality of second spectral reflectances which can be obtained bymeasurement relating to the plurality of samples using the secondspectrocolorimetric device and a reflectance difference as a deviationcomponent relating to the reflectance is acquired on the basis of ameasurement result in the step (a). Then, in the step (c), in a settingunit, a conversion rule for converting a spectral reflectance acquiredby measurement using the first spectrocolorimetric device into aspectral reflectance that can be acquired by measurement using thesecond spectrocolorimetric device is set on the basis of a relationshipbetween a reflectance and a reflectance difference for each wavelengthacquired in the step (b).

Advantageous Effects of Invention

According to the spectrocolorimetric device of one aspect, since therelationship between the reflectance and the reflectance difference foreach wavelength is set separately from the deviation relating to thespectral sensitivity, a highly-accurate conversion rule of measurementvalues between the different spectrocolorimetric devices can be easilyset.

According to the conversion rule setting method according to anotheraspect, since the relationship between the reflectance and thereflectance difference for each wavelength can be easily obtained, ahighly-accurate conversion rule of measurement values between thedifferent spectrocolorimetric devices can be easily set.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically illustrating a configuration exampleof a first spectrocolorimetric device.

FIG. 2 is a diagram schematically illustrating a configuration exampleof a second spectrocolorimetric device.

FIG. 3 is a diagram schematically illustrating a configuration exampleof a light-receiving unit.

FIG. 4 is a diagram exemplifying first and second spectral reflectancesrelating to a red colorimetric object.

FIG. 5 is a diagram exemplifying a difference between first and secondspectral reflectances.

FIG. 6 is a diagram exemplifying a spectral reflectance of a transparentmember.

FIG. 7 is a diagram exemplifying a spectral sensitivity of eachlight-receiving element of a light-receiving unit.

FIG. 8 is a diagram exemplifying a functional configuration realized bya control unit of a first spectrocolorimetric device.

FIG. 9 is a diagram exemplifying a functional configuration realized bya control unit of a second spectrocolorimetric device.

FIG. 10 is a diagram exemplifying a spectral reflectance acquired for anachromatic colorimetric object.

FIG. 11 is a diagram exemplifying a difference between spectralreflectances acquired for the same achromatic colorimetric objectbetween devices.

FIG. 12 is a diagram exemplifying a functional configuration realized bya control unit of a first spectrocolorimetric device.

FIG. 13 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 14 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 15 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 16 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 17 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 18 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 19 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 20 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 21 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 22 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 23 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 24 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 25 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 26 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 27 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 28 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 29 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 30 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 31 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 32 is a diagram illustrating a relationship between a spectralreflectance and a spectral reflectance difference.

FIG. 33 is a diagram exemplifying first and second spectral reflectancesacquired by measurement using first and second spectrocolorimetricdevices.

FIG. 34 is a diagram exemplifying a difference between first and secondspectral reflectances.

FIG. 35 is a diagram exemplifying a difference between a corrected firstspectral reflectance obtained by subtracting a reflectance differencefrom the first spectral reflectance and a second spectral reflectance.

FIG. 36 is a flowchart illustrating an operation flow relating tosetting of conversion rules.

FIG. 37 is a diagram exemplifying spectral reflectances of a pluralityof samples used for matching.

FIG. 38 is a diagram exemplifying a normal distribution functionindicating a spectral sensitivity in one light-receiving element.

FIG. 39 is a flowchart illustrating an operation flow of converting aspectroscopic spectrum obtained by measurement using a firstspectrocolorimetric device into a spectral reflectance that can beacquired by a second spectrocolorimetric device.

FIG. 40 is a diagram exemplifying a relationship between an amount ofincident light and an output in first and second spectrocolorimetricdevices.

FIG. 41 is a diagram schematically illustrating a configuration exampleof a first spectrocolorimetric device.

FIG. 42 is a diagram exemplifying spectral reflectances of two types oftransparent members.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention and various modifiedexamples are described with reference to the drawings. In addition, inthe drawings, components having the same configuration and function aredenoted by the same reference numerals, and redundant descriptionthereof is omitted. In addition, the drawings are schematicallyillustrated, and the sizes, positional relationships, and the like ofthe various structures in each figure can be appropriately changed.

(1) EMBODIMENT

<(1-1) Outline of Embodiment>

For example, between different spectrocolorimetric devices, even thoughan object of colorimetry (also referred to as a colorimetric object) isthe same, depending on a difference in optical system and a differencein wavelength calibration method, or the like, measurement values of thespectral reflectance may be different from each other. For this reason,if different spectrocolorimetric devices are used in parallel formeasurement with respect to similar colorimetric objects such as thesame products, in some cases, the spectral reflectances obtained for thespectrocolorimetric devices and the color values calculated from thespectral reflectances may be different. In this case, it is difficult toappropriately manage the color of the colorimetric object.

With respect to such a problem, in a first spectrocolorimetric device 1m (refer to FIG. 1) according to an embodiment, a spectral reflectance(also referred to as a first spectral reflectance) acquired bymeasurement using the first spectrocolorimetric device 1 m may beconverted into a spectral reflectance (also referred to as a secondspectral reflectance) that can be acquired by measurement using a secondspectrocolorimetric device 1 t (refer to FIG. 2) different from thefirst spectrocolorimetric device 1 m. At this time, the secondspectrocolorimetric device 1 t is another spectrocolorimetric device(also referred to as a destination-of-conversion spectrocolorimetricdevice) as a destination-of-conversion of the first spectral reflectanceobtained by the first spectrocolorimetric device 1 m. In addition, inthe embodiment, for example, the first and second spectrocolorimetricdevices 1 m and 1 t may be devices of different models or differentdevices of the same model.

However, in order to set a rule (also referred to as a conversion rule)for converting the first spectral reflectance into the second spectralreflectance by using the above-described Mathematical Formula (1) in therelated art, it is necessary to prepare a large number of calibrationsamples, and it takes a long time to perform the measurement using alarge number of the calibration samples. Furthermore, it is not easy tosecure a conversion accuracy (robustness) depending on a method ofselecting the calibration sample. For this reason, complicatedmanipulations or operations are required for setting a conversion rule,and it is not easy to set the conversion rule at a high accuracy.

Therefore, in the embodiment, the deviation between the first spectralreflectance and the second spectral reflectance is treated to be dividedinto the deviation (appropriately abbreviated to the deviation relatingto linearity) relating to linearity of the reflectance and the deviationrelating to the spectral sensitivity, and the conversion rule is set.Therefore, it is possible to set the conversion rule by using a smallnumber of calibration samples. Namely, a highly-accurate conversion ruleof measurement values between different spectrocolorimetric devices canbe easily set.

Herein, a deviation relating to the linearity is, for example, adeviation (also referred to as a first deviation) of the spectralreflectance in the reflectance direction occurring due to a differencein a relationship between an intensity of reflected light actuallygenerated on a colorimetric object for each wavelength and an intensityof reflected light to be measured between the devices. In other words,the deviation relating to the linearity corresponds to a difference(also referred to as a reflectance difference) of the reflectance as acomponent of the deviation (also referred to as a deviation component)relating to the reflectance for each wavelength between the firstspectral reflectance and the second spectral reflectance. In addition, adeviation relating to the spectral sensitivity is, for example, adeviation (also referred to as a second deviation) of spectralreflectance in the wavelength direction as an error (also referred to asa calibration error) occurring due to different wavelength calibrationmethods between the devices in calibrating the spectral sensitivity.

<(1-2) Schematic Configuration of Spectrocolorimetric Device>

FIG. 1 is a diagram schematically illustrating a configuration exampleof a first spectrocolorimetric device 1 m according to an embodiment.FIG. 2 is a diagram schematically illustrating a configuration exampleof a second spectrocolorimetric device 1 t. Herein, an example where theconfiguration of 45/0 (45° illumination and vertical reception)recommended by the International Commission on Illumination (CIE) isemployed will be described. For example, the configuration of 0/45(vertical illumination and 45° reception) recommended by the CIE may beemployed.

For example, each of the first and second spectrocolorimetric devices 1m and 1 t is configured to have a housing 2 and a light source 11, alight-emitting circuit 12, a light-receiving unit 13, a control unit 14,a storage unit 15 and an input/output unit 16 which are enclosed in thehousing 2.

The housing 2 is configured to have an opening 2 o. Herein, an exampleis employed where the second spectrocolorimetric device 1 t is providedwith a transparent member (also referred to as a transparent member) 17t for preventing particles (dust or the like) from intruding into thehousing 2 through the opening 2 o whereas the first spectrocolorimetricdevice 1 m is not provided with a transparent member. The transparentmember 17 t has a shape of, for example, a convex lens or a plate, andas a material of the transparent member 17 t, for example, colorlesstransparent glass or acrylic or the like may be employed. The opening 2o passes the light (also referred to as illumination light) emitted fromthe light source 11 toward the outside of the housing 2, so that acolorimetric object 100 arranged in the vicinity of the opening 2 ooutside the housing 2 is irradiated with the illumination light. Theopening 2 o passes the reflected light generated on the surface of thecolorimetric object 100 according to the irradiation of the colorimetricobject 100 with the illumination light emitted from the light source 11toward the inside of the housing 2.

The light source 11 emits, for example, white light. As the light source11 emitting white light, for example, a lamp such as a xenon (Xe) flashlamp may be employed.

The light-emitting circuit 12 is a circuit that allows the light source11 to emit light under the control of the control unit 14.

The light-receiving unit 13 spectroscopically disperses the reflectedlight generated on the surface of the colorimetric object 100 accordingto the irradiation of the colorimetric object 100 with the illuminationlight emitted from the light source 11 and measures the spectroscopicspectrum relating to the intensity of the reflected light. FIG. 3 is adiagram schematically illustrating a configuration example of thelight-receiving unit 13. As illustrated in FIG. 3, the light-receivingunit 13 is configured to include, for example, a slit plate 131, aspectroscopic unit 132, and a sensor unit 133.

The slit plate 131 is a plate-shaped member having a slit-shaped opening(also referred to as a slit portion) 131 s for allowing a portion oflight (also referred to as incident light) L0 of the reflected lightfrom the colorimetric object 100 to be incident into the light-receivingunit 13.

The spectroscopic unit 132 is a member that spectroscopically dispersesthe incident light L0 incident from the slit portion 131 s according tothe wavelength and is configured with, for example, a diffractiongrating or the like. In addition, in FIG. 3, among the light beams of aplurality of wavelengths obtained by spectroscopically dispersing theincident light L0 by the spectroscopic unit 132, the outer edge of thelight flux of red light (also referred to as red light) Lr1 is drawn bya solid arrow, and the outer edge of the light flux of blue light (alsocalled blue light) Lb1 is drawn by a one-dot dashed line.

The sensor unit 133 is a unit that measures the intensity of lightspectroscopically dispersed by the spectroscopic unit 132 for eachwavelength and is configured to include, for example, a line sensor(also referred to as a linear array sensor) where a plurality oflight-receiving elements arranged in a line.

In the light-receiving unit 13 having such a configuration, the incidentlight L0 incident from the slit portion 131 s is spectroscopicallydispersed by the spectroscopic unit 132 and then emitted to the sensorunit 133, so that the intensity of light for each wavelength of theincident light L0 is measured by the sensor unit 133.

The control unit 14 is an electric circuit that performs various typesof information processing and is configured to mainly include aprocessor P0 and a memory M0. In the control unit 14, the processor P0reads and executes a program (a program P1 in the firstspectrocolorimetric device 1 m and a program P2 in the secondspectrocolorimetric device 1 t) stored in the storage unit 15, so thatfunctions of controlling each unit and performing various operations inthe first spectrocolorimetric device 1 m (or the secondspectrocolorimetric device 1 t) are realized. The memory M0 is, forexample, a volatile storage medium such as a RAM and temporarily storesdata generated by various operations in the control unit 14.

The storage unit 15 is configured with, for example, a nonvolatilestorage medium and stores programs (the program P1 in the firstspectrocolorimetric device 1 m and the program P2 in the secondspectrocolorimetric device 1 t) and various types of information and thelike used for various calculations in the control unit 14. In addition,in the first and second spectrocolorimetric devices 1 m and 1 t, sincethe programs P1 and P2 executed by the control unit 14 are different,the various functions realized by the control unit 14 are different.

The input/output unit 16 includes, for example, an operation unit, adisplay unit, and the like. The input/output unit 16 has, for example, afunction of inputting signals according to operations of the operationunit by a user and a function of visibly outputting various types ofinformation and the like as calculation results in the control unit 14on the display unit.

<(1-3) Deviation of Spectral Reflectance between Devices>

FIG. 4 is a graph exemplifying the spectral reflectance (first spectralreflectance) R_(m)(λ) measured by the first spectrocolorimetric device 1m and the spectral reflectance (second spectral reflectance) R_(t)(λ)measured by the second spectrocolorimetric device 1 t for the same redtile as the colorimetric object 100. In addition, in FIG. 4, thehorizontal axis indicates the wavelength λ of the light, and thevertical axis indicates the spectral reflectance R(λ) on the surface ofthe colorimetric object 100. FIG. 5 is a graph exemplifying thedifference ΔR(λ) (=R_(m)(λ)−R_(t)(λ)) between the first spectralreflectance R_(m)(λ) obtained by the first spectrocolorimetric device 1m and the second spectral reflectance R_(t)(λ)obtained by the secondspectrocolorimetric device 1 t. In FIG. 5, the horizontal axis indicatesthe wavelength λ, the vertical axis indicates the reflectance differenceΔR, and the relationship between the wavelength λ and the reflectancedifference ΔR is drawn by a solid line.

As illustrated in FIG. 5, even when the same red tile is measured, themeasurement values of the spectral reflectance are different between thedevices. The deviation in spectral reflectance between the devices isclassified into the first deviation relating to the linearity and thesecond deviation relating to the spectral sensitivity as describedabove. Herein, the first deviation relating to the linearity and thesecond deviation relating to the spectral sensitivity will bespecifically described.

<(1-3-1) Deviation Relating to Linearity (First Deviation)>

FIG. 6 is a diagram illustrating an example of a spectral reflectance ofthe transparent member 17 t. The transparent member 17 t provided in thesecond spectrocolorimetric device 1 t exhibits a spectral reflectance asillustrated in FIG. 6, for example, by antireflection coating applied tothe surface.

As illustrated in FIG. 2, in the second spectrocolorimetric device 1 t,for example, after the irradiation light emitted from the light source11 is reflected on the surface of the colorimetric object 100, the lightpassing through the transparent member 17 t and further the light thatis retroreflected, namely, sequentially reflected on the surface of thetransparent member 17 t and the surface of the colorimetric object 100and then passes through the transparent member 17 t is received by thelight-receiving unit 13. On the other hand, as illustrated in FIG. 1, inthe first spectrocolorimetric device 1 m, for example, after theirradiation light emitted from the light source 11 is reflected on thesurface of the colorimetric object 100, the light is simply received bythe light-receiving unit 13. As described above, even when thecolorimetric object 100 is the same between the first and secondspectrocolorimetric devices 1 m and 1 t, since the paths of light fromthe light source 11 to the light-receiving unit 13 are different, theacquired spectral reflectances may be different.

Herein, for example, in the first and second spectrocolorimetric devices1 m and 1 t, white calibration using a white calibration plate having areflectance of about 100% and black calibration using a blackcalibration plate having a reflectance of about 0% are assumed to beperformed. In this case, if the colorimetric object 100 is white, thespectroscopic spectrum priced for the white calibration plate can bemeasured by the first and second spectrocolorimetric devices 1 m and 1t, respectively. In addition, if the colorimetric object 100 is black,spectroscopic spectrum priced for the black calibration plate can bemeasured by the first and second spectrocolorimetric devices 1 m and 1t, respectively. Namely, if the colorimetric object 100 is white orblack, the same spectral reflectance can be acquired between the firstand second spectrocolorimetric devices 1 m and 1 t, respectively. On theother hand, in the case where the colorimetric object 100 has anapproximately intermediate reflectance (for example, about 50%) betweenwhite and black, in the spectroscopic spectra measured by the first andsecond spectrocolorimetric devices 1 m and 1 t, respectively, thelargest deviation caused by retroreflection may occur.

In addition, as illustrated in FIG. 6, the spectral reflectance of thetransparent member 17 t is not constant with respect to the wavelength.For this reason, for example, with respect to a wavelength at which thereflectance of the transparent member 17 t is 0%, no retroreflectionoccurs between the transparent member 17 t and the colorimetric object100. On the other hand, as for the wavelength of the transparent member17 t having a relatively high reflectance, the deviation of the acquiredspectral reflectance greatly differs between the devices due to theretroreflection between the transparent member 17 t and the colorimetricobject 100. As described above, the first deviation relating to thelinearity caused by the retroreflection among the acquired spectralreflectances differs depending on the wavelength of light and thereflectance of the colorimetric object 100.

In addition, in the examples illustrated in FIGS. 4 and 5, in thewavelength range in the vicinity of 650 to 740 nm, the change inreflectance with respect to the change in wavelength is relativelysmall. Therefore, among the deviations of the spectral reflectanceacquired between the devices illustrated in FIGS. 4 and 5, the deviationin spectral reflectance at a wavelength in the vicinity of 650 to 740 nmcorresponds to the first deviation relating to the linearity due toretroreflection.

<(1-3-2) Deviation Relating to Spectral Sensitivity (Second Deviation)>

FIG. 7 is a diagram illustrating a spectral sensitivity of eachlight-receiving element constituting the sensor unit 133 of thelight-receiving unit 13. In the first and second spectrocolorimetricdevices 1 m and 1 t, the respective light-receiving units 13 havedifferent spectral sensitivities. For this reason, for example, afunction (for example, a function that defines a center wavelength, afull width at half maximum, or the like) that defines the spectralsensitivity of each light-receiving element is calibrated by differentwavelength calibration methods for different devices, so that thecorrection according to the spectral sensitivity of each light-receivingelement can be performed. Herein, as a wavelength calibration method,for example, there are a number of calibration methods such as acalibration method using a monochromator and a calibration method usinga bright-line light source, or the like as described below, and thus,different wavelength calibration methods for different models may beemployed.

In the calibration method using a monochromator, for example,monochromatic light emitted by a monochromator is incident on aspectrocolorimetric device while the wavelength of the monochromaticlight being shifted in time, and thus, the wavelength is calibrated sothat the spectroscopic spectrum of monochromatic light of eachwavelength coincides with the spectroscopic spectrum detected by thespectrocolorimetric device. In addition, as the pitch at which thewavelength of the monochromatic light is shifted, for example, 1 nm orthe like may be employed. However, in the calibration method using themonochromator, since monochromatic light of each wavelength tends tohave a weak light amount, the exposure time for receiving monochromaticlight in the spectrocolorimetric device can be increased. Furthermore,the number of scanning wavelength points of monochromatic light of aplurality of wavelengths is very large, and thus, it takes a long timeto calibrate the wavelength.

In the calibration method using the bright-line light beams, forexample, light beams of a plurality of specific wavelengths emitted fromthe bright-line light source are input to the spectrocolorimetricdevice, and the wavelength is calibrated so that spectroscopic spectrumrelating to the intensity of the light beam of each of the specificwavelengths coincides with the spectroscopic spectrum detected by thespectrocolorimetric device. In addition, as the bright-line lightsource, for example, a mercury lamp, a mercury cadmium lamp, or the likemay be employed. With respect to the calibration method using thebright-line light beams, for example, light beams of a plurality ofspecific wavelengths are simultaneously emitted from the bright-linelight beams, and light amounts of the light beams of the respectivespecific wavelengths are also high, so that the time required forcalibration can be shortened. However, in the calibration method usingthe bright-line light beams, the calibration accuracy is low forwavelengths deviated from a plurality of specific wavelengths.

Herein, if the wavelength calibration methods are different between thefirst and second spectrocolorimetric devices 1 m and 1 t, for example,the accuracies of the calibration relating to the center wavelength andthe full width at half maximum of the spectral sensitivities of thelight-receiving elements between the first and secondspectrocolorimetric devices 1 m and 1 t are different from each other.In addition, if the wavelength calibration methods are different betweenthe first and second spectrocolorimetric devices 1 m and 1 t, eventhough the colorimetric object 100 is the same, the spectroscopicspectra of the reflected light acquired by the spectrocolorimetricdevices 1 m and 1 t are different from each other. Specifically, betweenthe first and second spectrocolorimetric devices 1 m and 1 t, thespectral reflectance acquired according to the difference in thewavelength calibration method may be deviated in the wavelengthdirection, or the waveform of the spectral reflectance may be corruptedso that a difference in the spectral reflectance occurs as a measurementresult.

In addition, in the example illustrated in FIGS. 4 and 5, in thewavelength range in the vicinity of 550 to 650 nm, the change inreflectance with respect to the change in wavelength is large.Therefore, among the deviations of the spectral reflectances acquiredbetween the devices illustrated in FIGS. 4 and 5, the deviation inspectral reflectance at a wavelength in the vicinity of 550 to 650 nmcorresponds to the second deviation relating to the spectralsensitivity.

<(1-4) Correction of Deviation in Spectral Reflectance between Devices>

For example, if the first and second spectrocolorimetric devices 1 m and1 t are products of the same manufacturer and the firstspectrocolorimetric device 1 m is a successor of the secondspectrocolorimetric device 1 t, a user may expect that the measurementvalues similar to those of the second spectrocolorimetric device 1 t canbe obtained for the same colorimetric object 100 by the firstspectrocolorimetric device 1 m. In order to respond to such expectation,in the embodiment, the deviation in spectral reflectance between thedevices is considered, and the spectral reflectance acquired by thefirst spectrocolorimetric device 1 m is converted to the spectralreflectance that can be acquired the second spectrocolorimetric device 1t.

As described above, the deviation in spectral reflectance between thedevices is a mixture of the first deviation relating to the linearityand the second deviation relating to the spectral sensitivity.Therefore, if the first deviation relating to the linearity and thesecond deviation relating to the spectral sensitivity are notdistinguished from each other, it is necessary to employ such a methodas to set a conversion rule for converting the first spectralreflectance into the second spectral reflectance by using, for example,the above-described Mathematical Formula (1) in the related art.However, Mathematical Formula (1) is a very complicated formula, and thecoefficients A(i), B(i), C(i), D(i), and E(i) need to be obtained foreach wavelength λ(i) of each light receiving element. Therefore, it isnecessary to prepare a large number of calibration samples, and it takesa long time to perform the measurement using a large number of thecalibration samples. In addition, the robustness of the coefficientsA(i), B(i), C(i), D(i), and E(i) to be obtained may be deteriorateddepending on the characteristics of the calibration sample.

Therefore, in the embodiment, the deviation between the first spectralreflectance acquired by the first spectrocolorimetric device 1 m and thesecond spectral reflectance acquired by the second spectrocolorimetricdevice 1 t is treated to be divided into the first deviation relating tothe linearity and the second deviation relating to the spectralsensitivity, and the conversion rule is set. As a result, by using asmall number of calibration samples, a highly-accurate conversion ruleof measurement values between different spectrocolorimetric devices canbe easily set.

In addition, for example, if both the first and secondspectrocolorimetric devices 1 m and 1 t are products of the samemanufacturer, information relating to various types of calibration isknown by the manufacturer. Therefore, in the first spectrocolorimetricdevice 1 m, for example, by using information on various types of knowncalibration, a highly-accurate conversion rule of measurement valuesbetween different spectrocolorimetric devices can be easily set.

FIG. 8 is a diagram exemplifying a functional configuration realized bythe control unit 14 of the first spectrocolorimetric device 1 m in orderto correct the deviation in spectral reflectance between the devices.

As illustrated in FIG. 8, the control unit 14 of the firstspectrocolorimetric device 1 m is configured to include a calculationunit 14 ma, an acquisition unit 14 mb, and a conversion unit 14 mc, as afunctional configuration realized by executing the program P1 by theprocessor P0.

The calculation unit 14 ma calculates the spectral reflectance (firstspectral reflectance) of the colorimetric object 100 from thespectroscopic spectrum relating to the reflected light from thecolorimetric object 100 measured by the light-receiving unit 13 of thefirst spectrocolorimetric device 1 m. In the calculation unit 14 ma, forexample, the first spectral reflectance can be calculated on the basisof the preset spectroscopic spectrum of the light emitted from the lightsource 11 and the spectroscopic spectrum relating to the measuredreflected light.

The acquisition unit 14 mb acquires the reflectance difference as thedeviation component relating to the reflectance for each wavelength ofthe light between the first spectral reflectance and the second spectralreflectance on the basis of the first spectral reflectance calculated bythe calculation unit 14 ma and relationship information A1 stored in thestorage unit 15. Herein, the relationship information A1 is informationindicating the relationship between the reflectance and the reflectancedifference for each wavelength of light and is information defining aconversion rule (also referred to as a first conversion rule) forcorrecting the first deviation relating to the linearity in order toconvert the first spectral reflectance R_(m)(λ) into the second spectralreflectance R_(t)(λ).

Herein, the first spectral reflectance R_(m)(λ) is obtained by actualmeasurement using the first spectrocolorimetric device 1 m. The secondspectral reflectance R_(t)(λ)is an estimated value (also referred to asa second estimated spectral reflectance) that is estimated to beobtained by measurement using the second spectrocolorimetric device 1 tas a destination-of-conversion spectrocolorimetric device different fromthe first spectrocolorimetric device 1 m. For example, the reflectancedifference for each wavelength can be acquired, for example, on thebasis of the difference between the spectral reflectance obtained bymeasurement using the first spectrocolorimetric device 1 m and thespectral reflectance obtained by measurement using the secondspectrocolorimetric device 1 t for the same calibration sample inadvance. Therefore, for example, for each wavelength, the relationshipbetween the reflectance and the reflectance difference corresponding tothe first spectral reflectance acquired by measurement using the firstspectrocolorimetric device 1 m can be acquired.

The conversion unit 14 mc adds or subtracts the reflectance differencefor each wavelength acquired by the acquisition unit 14 mb to or fromthe first spectral reflectance calculated by the calculation unit 14 mato convert the first spectral reflectance into the second spectralreflectance. Herein, for example, if the reflectance difference definedby the relationship information A1 represents the magnitude of the firstspectral reflectance with respect to the second spectral reflectance asa reference as a positive/negative numerical value, the conversion unit14 mc may substrate the reflectance difference for each wavelengthacquired by the acquisition unit 14 mb from the first spectralreflectance calculated by the calculation unit 14 ma. Conversely, if thereflectance difference represents the magnitude of the second spectralreflectance with respect to the first spectral reflectance as areference, the conversion unit may add the reflectance difference to thefirst spectral reflectance.

In the case where such a configuration is employed, in addition to thesecond deviation relating to the spectral sensitivity, for the firstdeviation relating to the linearity, the relationship between thereflectance for each wavelength and the reflectance difference as adeviation component relating to the reflectance is set. Therefore, inorder to correct the first deviation relating to the linearity, ahighly-accurate conversion rule of measurement value between thedifferent first and second spectrocolorimetric devices 1 m and 1 t canbe easily set.

In addition, the conversion unit 14 mc can calculate the estimated value(second estimated spectral reflectance) R*_(t)(λ*_(G) _(_) _(t)(k)) ofthe spectral reflectance that is estimated to be acquired in the secondspectrocolorimetric device 1 t from the spectroscopic spectrum by usingthe calibrated spectral sensitivity (also referred to as the calibratedspectral sensitivity) of the second spectrocolorimetric device 1 tdifferent from the first spectrocolorimetric device 1 m and thespectroscopic spectrum measured by the light-receiving unit 13 of thefirst spectrocolorimetric device 1 m. Herein, k is a natural number of 1to K0 for defining the wavelength and may be, for example, a numericalvalue that defines the order of the first to K₀-th light-receivingelements in the sensor unit 133.

In the case where such a configuration is employed, in addition to thefirst deviation relating to linearity, information (also referred to ascalibrated spectral sensitivity information) S1 indicating thecalibrated spectral sensitivity with respect to the deviation relatingto the spectral sensitivity is set. Namely, the calibrated spectralsensitivity information S1 is information defining a conversion rule(also referred to as a second conversion rule) for correcting the seconddeviation relating to the spectral sensitivity to convert the firstspectral reflectance R_(m)(λ) to the second spectral reflectanceR_(t)(λ). As a result, in order to correct the second deviation relatingto the spectral sensitivity, a highly-accurate conversion rule of themeasurement value between the different first and secondspectrocolorimetric devices lm and 1 t can be easily set.

In addition, as described above, the conversion unit 14 mc adds orsubtracts the reflectance difference for each wavelength acquired by theacquisition unit 14 mb to or from the first spectral reflectanceR_(m)(λ), and the second spectral reflectance R_(t)(λ)that can beacquired by the second spectrocolorimetric device 1 t from thespectroscopic spectrum may be calculated by using the calibratedspectral sensitivity information S1 of the second spectrocolorimetricdevice 1 t and the spectroscopic spectrum measured by the firstspectrocolorimetric device 1 m. At this time, for example, theconversion unit 14 mc adds or subtracts the reflectance difference foreach wavelength acquired by the acquisition unit 14 mb to or from thespectral reflectance acquired by using the spectroscopic spectrum andthe calibrated spectral sensitivity, so that the second spectralreflectance that can be acquired by the second spectrocolorimetricdevice 1 t is calculated.

In the case where such a configuration is employed, the differencebetween the first spectral reflectance R_(m)(λ) acquired by the firstspectrocolorimetric device 1 m and the second spectral reflectanceR_(t)(λ) acquired by the second spectrocolorimetric device 1 t isdivided into the first deviation relating to the linearity and thesecond deviation relating to the spectral sensitivity, and thus, theconversion rule is set. Thus, in order to correct the first deviationrelating to the linearity and the second deviation relating to thespectral sensitivity, it is possible to set the conversion rule by usinga relatively small number of calibration samples. Namely, ahighly-accurate conversion rule of measurement values between thedifferent first and second spectrocolorimetric devices 1 m and 1 t canbe easily set.

FIG. 9 is a diagram exemplifying a functional configuration realized bythe control unit 14 of the second spectrocolorimetric device 1 t. Asillustrated in FIG. 9, the control unit 14 of the secondspectrocolorimetric device 1 t has a calculation unit 14 ta as afunctional configuration realized by executing the program P2 by theprocessor P0. The calculation unit 14 ta calculates the spectralreflectance (the second spectral reflectance) R_(t)(λ) relating to thecolorimetric object 100 from the spectroscopic spectrum relating to thereflected light from the colorimetric object 100 measured by thelight-receiving unit 13 of the second spectrocolorimetric device 1 t. Inthe calculation unit 14 ta, for example, the second spectral reflectancecan be calculated on the basis of the preset spectroscopic spectrum ofthe light emitted from the light source 11 and the spectroscopicspectrum relating to the measured reflected light.

Hereinafter, the correction of the first deviation relating to thelinearity between the devices and the correction of the second deviationrelating to the spectral sensitivity will be sequentially described.

<(1-4-1) Correction of Deviation (First Deviation) Relating to Linearitybetween Devices>

For example, in the case where the colorimetric object 100 has aspectral reflectance so that the reflectance is substantially constantirrespective of the wavelength of light, an error (a second deviationrelating to the spectral sensitivity) of the spectral reflectance due tothe deviation of the spectral sensitivity between the devices is hardlygenerated. Specifically, for example, if the reflectance issubstantially constant irrespective of the wavelength in the spectralreflectance, even though the center wavelength and the full width athalf maximum that define the spectral sensitivity in eachlight-receiving element are deviated between the devices, thespectroscopic spectrum relating to the intensity of the light receivedin each of the light-receiving elements is hardly changed. As describedabove, as the colorimetric object 100 having a spectral reflectance, ofwhich reflectance is substantially constant irrespective of thewavelength of light, for example, a calibration sample of whichreflectance is included within a width of the predetermined value rangein the entire to-be-measured wavelength range may be exemplified.

Herein, as the to-be-measured wavelength achromatic range, for example,a wavelength range of about 360 to 740 nm which is a wavelength range ofvisible light may be employed. As the predetermined value range, forexample, a very narrow preset value range may be employed. As thecolorimetric object 100 satisfying such a condition, for example, anachromatic sample may be exemplified.

FIG. 10 is a diagram exemplifying a spectral reflectance acquired forthe colorimetric object 100 of an achromatic color. In FIG. 10, forachromatic samples with a plurality of types of density ranging fromwhite to black, examples of the first and second spectral reflectancesR_(m)(λ) and R_(t)(λ) acquired by the first and secondspectrocolorimetric devices 1 m and 1 t, respectively, are illustratedby curves. Specifically, the first and second spectral reflectancesR_(m)(λ) and R_(t)(λ)are illustrated in a graph in which the horizontalaxis is the wavelength λ and the vertical axis is the reflectance R.

FIG. 11 is a diagram exemplifying a difference of the spectralreflectance between the devices acquired for the same achromaticcolorimetric object 100. In FIG. 11, for achromatic samples with aplurality of types of density ranging from white to black, a differenceΔR(λ) (=R_(m)(λ)−R_(t)(λ)) between the first spectral reflectanceR_(m)(λ) acquired by the first spectrocolorimetric device 1 m and thesecond spectral reflectance R_(t)(λ)acquired by the secondspectrocolorimetric device 1 t is illustrated.

In FIGS. 10 and 11, in the wavelength range of 360 to 400 nm and thewavelength range of 650 to 740 nm where the reflectance of thetransparent member 17 t is high, between the first and secondspectrocolorimetric devices 1 m and 1 t, a state that a deviation inspectral reflectance between the devices occurs is illustrated. Herein,with respect to the wavelength range excluding the wavelength rangewhere the spectral reflectance of the colorimetric object 100 ischanging, the difference (reflectance difference) ΔR(λ) between thefirst spectral reflectance R_(m)(λ) acquired by the firstspectrocolorimetric device 1 m and the second spectral reflectanceR_(t)(λ)acquired by the second spectrocolorimetric device 1 tcorresponds to the first deviation relating to the linearity.

As described above, by using the colorimetric object 100 of whichspectral reflectance is substantially constant as a calibration sample,the first deviation relating to the linearity in which the influence ofthe second deviation relating to the spectral sensitivity among thedeviations in spectral reflectance acquired between the devices iseliminated can be detected. As a result, a plurality of calibrationsamples for obtaining the relationship between the reflectance for eachwavelength and the reflectance difference as a deviation componentrelating to the reflectance can be easily prepared. Namely, therelationship between the reflectance for each wavelength and thereflectance difference as a deviation component relating to thereflectance can be easily obtained.

Herein, the setting of the relationship information A1 indicating therelationship between the reflectance and the reflectance difference foreach wavelength will be specifically described.

FIG. 12 is a diagram exemplifying a functional configuration realized bythe control unit 14 of the first spectrocolorimetric device 1 m in orderto set the relationship information A1 as a first change rule forcorrecting the first deviation relating to the linearity between thedevices.

As illustrated in FIG. 12, the control unit 14 of the firstspectrocolorimetric device 1 m is configured to include a calculationunit 14 ma, an arithmetic unit 14 md, and a setting unit 14 me as afunctional configuration realized by executing the program P1 in thestorage unit 15 by the processor P0.

The arithmetic unit 14 md acquires a relationship between thereflectance and the reflectance difference for each wavelength between aplurality of the first spectral reflectances acquired by measurementusing the first spectrocolorimetric device 1 m and a plurality of thesecond spectral reflectances acquired by measurement using the secondspectrocolorimetric device 1 t. Herein, the plurality of first spectralreflectances can be acquired by measurement relating to a plurality ofsamples using the first spectrocolorimetric device 1 m, respectively.For example, with respect to each of the achromatic calibration samples,the calculation unit 14 ma can calculate the first spectral reflectancerelating to the colorimetric object 100 on the basis of thespectroscopic spectrum relating to the reflected light from thecolorimetric object 100 measured by the light-receiving unit 13 of thefirst spectrocolorimetric device 1 m. In addition, the plurality ofsecond spectral reflectances can be acquired by measurement relating toa plurality of samples using the second spectrocolorimetric device 1 t,respectively. For example, with respect to each of the achromaticcalibration samples, the calculation unit 14 ta can calculate the secondspectral reflectance relating to the colorimetric object 100 from thespectroscopic spectrum relating to the reflected light from thecolorimetric object 100 measured by the light-receiving unit 13 of thesecond spectrocolorimetric device 1 t.

The setting unit 14 me sets the relationship information A1 as aconversion rule for converting the first spectral reflectance R_(m)(λ)acquired by measurement using the first spectrocolorimetric device 1 mto the second spectral reflectance R_(t)(λ) that can be acquired bymeasurement using the second spectrocolorimetric device 1 t on the basisof the relationship between the reflectance and the reflectancedifference for each wavelength acquired by the arithmetic unit 14 md.

FIGS. 13 to 32 are diagrams illustrating the relationships between thefirst spectral reflectance R_(m)(λ) and the reflectance differenceΔR(λ). Herein, the first spectral reflectance R_(m)(λ) is a measurementvalue acquired by actual measurement using the first spectrocolorimetricdevice 1 m for plural types of achromatic calibration samples havingdifferent densities. The reflectance difference ΔR(λ) is the differencebetween the first spectral reflectance R_(m)(λ) acquired by actualmeasurement using the first spectrocolorimetric device 1 m and thesecond spectral reflectance R_(t)(λ) acquired by actual measurementusing the second spectrocolorimetric device 1 t for each of the pluraltypes of achromatic calibration samples having different densities.

FIGS. 13 to 32 illustrate the relationship between the first spectralreflectance R_(m)(λ) and the reflectance difference ΔR(λ) for eachwavelength λ(λ=360, 380, 400, . . . , 740 nm) at intervals of 20 nm inthe range of 360 to 740 nm. In addition, in each of FIGS. 13 to 32, thedata indicated by open circles are data obtained for wavelength rangesin which the spectral reflectance of each calibration sample issubstantially constant. In addition, the curves drawn by solid linesapproximately indicate the relationship between the first spectralreflectance R_(m)(λ) and the reflectance difference ΔR(λ) for eachwavelength. Herein, in the case where the first and second spectralreflectances R_(m)(λ) and R_(t)(λ)for each wavelength become about 50%by performing the white calibration and the black calibration in thefirst and second spectrocolorimetric devices 1 m and 1 t, respectively,the example where the reflectance difference ΔR(λ) exhibits a maximumvalue is illustrated.

On the other hand, with respect to the colorimetric object 100 which isdark and dark, the first spectral reflectance R_(m)(λ) has a smallvalue, and thus, an error due to measurement is likely to occur in thereflectance difference ΔR(λ). This error causes a decrease in theaccuracy of correction in the case of correcting the first deviationrelating to the linearity with respect to the chromatic colorimetricobject 100 at the time of performing actual colorimetry not forcalibration. For this reason, for the colorimetric object 100 having asmall first spectral reflectance R_(m)(λ), if the relationship betweenthe first spectral reflectance R_(m)(λ) and the reflectance differenceΔR(λ) is acquired while finely changing the first spectral reflectanceR_(m)(λ), the influence of the errors due to the measurement in thereflectance difference ΔR(λ) can be reduced.

For example, each of FIGS. 13 to 32 illustrates the mode where, withrespect to the first spectral reflectance R_(m)(λ) of 10% or less, therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) for a plurality of colorimetric objects 100having different densities is acquired by actual measurement. Inaddition, for example, with respect to the first spectral reflectanceR_(m)(λ) of above six levels such as 0, 5, 10, 20, 50, 100%, or thelike, if the relationship between the first spectral reflectanceR_(m)(λ) and the reflectance difference ΔR(λ) is acquired by actualmeasurement, the error in the reflectance difference ΔR(λ) due to themeasurement can be reduced to some extent. In addition, at this time,the spectral reflectance can be measured for a number of wavelengthscorresponding to the number of the plurality of light-receiving elementsby measurement for one calibration sample. Namely, data relating to alarge number of spectral reflectances can be acquired by using a smallnumber of calibration samples. As a result, the relationship informationA1 for converting the first spectral reflectance R_(m)(λ) to the secondspectral reflectance R_(t)(λ) can be easily acquired and set.

Herein, it is assumed that the relationship information A1 includes, forexample, a relational formula approximately representing therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) for each wavelength λ. Namely, it isassumed that the relational formula represents the relationship betweenthe reflectance and the reflectance difference for each wavelength.Then, by fitting the function of the N-th order represented byMathematical Formula (2) to the relationship between the first spectralreflectance R_(m)(λ) and the reflectance difference ΔR(λ) obtained byactual measurement, the coefficient a_(n)(λ) is obtained. InMathematical Formula (2), n is an integer of 0 to N, and N is anarbitrary integer of 2 or more which can be appropriately set. Herein,as a fitting of the N-th order function, for example, calculation usinga nonlinear least square method or the like may be employed. Inaddition, in the case where the first and second spectral reflectancesR_(m)(λ) and R_(t)(λ) are configured with spectral reflectances for 39wavelengths (360, 370, 380, . . . , 740 nm) with a pitch of 10 nm in thewavelength range of 360 to 740 nm, respectively, the coefficienta_(n)(λ) is obtained for each of the 39 wavelengths.

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 2} \right\rbrack & \; \\{{\Delta \; {R(\lambda)}} = {\sum\limits_{n = 0}^{N}{{a_{n}(\lambda)} \cdot \left\{ {R_{m}(\lambda)} \right\}^{n}}}} & (2)\end{matrix}$

By such fitting, a relational formula approximately representing therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) can be calculated. The calculation of therelational formula by fitting can be executed in the arithmetic unit 14md. However, the calculation of the relational formula by fitting may beexecuted by, for example, various types of information processingdevices other than the first spectrocolorimetric device 1 m.

Then, for example, the coefficient a_(n)(λ) and Mathematical Formula (2)for each wavelength λ obtained herein can be stored in the storage unit15 as the relationship information A1 by the setting unit 14 me. Namely,the setting unit 14 me can set the relationship information A1 as thefirst conversion rule. Namely, the relationship information A1 may beset on the basis of the first and second spectral reflectances R_(m)(λ)and R_(t)(λ) respectively acquired by measurement using the first andsecond spectrocolorimetric device 1 m and 1 t for each sample ofachromatic calibration samples of which spectral reflectances aredifferent from each other.

Accordingly, in the case where the first spectral reflectance R_(m)(λ)is acquired by measurement using the first spectrocolorimetric device 1m for any colorimetric object 100, the reflectance difference ΔR(λ)corresponding to the first deviation relating to the linearity betweenthe first and second spectrocolorimetric device 1 m and 1 t can becalculated by inserting the first spectral reflectance R_(m)(λ) intoMathematical Formula (2). Namely, the acquisition unit 14 mb can acquirethe reflectance difference ΔR(λ) for each wavelength λ by calculationusing the first spectral reflectance R_(m)(λ) of an arbitrarycolorimetric object 100 and the relational formula included in therelationship information A1. As a result, the conversion unit 14 mc canconvert the measurement value at a high accuracy and a high speedbetween the first and second spectrocolorimetric device 1 m and 1 twhich are different from each other.

Herein, for each wavelength λ, one N-th order function is fitted to aplurality of combinations of the first spectral reflectance R_(m)(λ) andthe reflectance difference ΔR(λ) obtained by actual measurement, but thepresent invention is not limited thereto.

For example, the first spectral reflectance R_(m)(λ) may be divided intoa plurality of regions, and an N-th function may be fitted to aplurality of combinations of the first spectral reflectance R_(m)(λ) andthe reflectance difference ΔR(λ) for each region. In this case, therelationship information A1 has a relational formula between the firstspectral reflectance R_(m)(λ) and the reflectance difference ΔR(λ) ineach of the plurality of reflectance regions for each wavelength. Inother words, for each wavelength λ, the coefficient a_(n)(λ) in each ofthe plurality of reflectance regions may be calculated and stored in thestorage unit 15. Herein, as the plurality of reflectance regions, aplurality of value ranges such as 0 to 10%, 10 to 50%, 50 to 100%, andthe like which the region of 0 to 100% is divided into may beexemplified. Accordingly, the accuracy approximately indicating therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) can be improved by the relational formulaobtained by the fitting. Therefore, a highly-accurate conversion rule ofmeasurement values between the different first and secondspectrocolorimetric device 1 m and 1 t can be more easily set.

For example, for each wavelength, a table indicating the relationshipbetween the first spectral reflectance R_(m)(λ) and the reflectancedifference ΔR(λ) by a plurality of combinations of the reflectance andthe reflectance difference may be stored as the relationship informationA1 in the storage unit 15. In this case, for example, the acquisitionunit 14 mb can acquire the reflectance difference ΔR(λ) for eachwavelength λ on the basis of the first spectral reflectance R_(m)(λ) ofthe arbitrary colorimetric object 100 and the table. As a result, theconversion unit 14 mc can convert the measurement value at a highaccuracy and a high speed between the first and secondspectrocolorimetric device 1 m and 1 t which are different from eachother. In the case where such a configuration is employed, since thetable indicating the relationship between the reflectance and thereflectance difference for each wavelength λ can be easily set, ahighly-accurate conversion rule of the measurement value between thefirst and second spectrocolorimetric device 1 m and 1 t can be easilyset.

With such a configuration, for example, the acquisition unit 14 mb canacquire the reflectance difference ΔR(λ) for each wavelength λ withrespect to the first spectral reflectance R_(m)(λ) relating to thearbitrary colorimetric object 100 by interpolation process using two ormore combinations of the reflectance and the reflectance differenceincluded in the table for each wavelength. Therefore, it is possible torealize a reduction in the storage capacity of the storage unit 15 and areduction in the number of calibration samples and the number of timesof measurement to obtain a large number of combinations of thereflectance and the reflectance difference. Namely, since the dataindicating the relationship between the reflectance and the reflectancedifference for each wavelength can be reduced, the data can be easilyacquired. As a result, a highly-accurate conversion rule of measurementvalues between the first and second spectrocolorimetric devices 1 m and1 t which are different from each other can be easily set.

Herein, for example, in the table of each wavelength, an example isassumed where the relationship between the reflectance and thereflectance difference is described for six reflectances of 0, 5, 10,20, 50, and 100%. In this example, for example, if 15% is acquired asthe first spectral reflectance R_(m)(λ) of an arbitrary colorimetricobject 100 by measurement using the first spectrocolorimetric device 1m, the reflectance difference corresponding to the reflectance of 15%can be acquired by an interpolation process using two combinations ofreflectance and reflectance difference for two levels of reflectance of10% and 20% in the table for each wavelength.

In addition, for example, if an example of storing combinations of thereflectances and the reflectance differences relating to a large numberof spectral reflectances with fine pitches in a table for eachwavelength is assumed, the storage capacity of the storage unit 15, thenumber of calibration samples for obtaining a large number ofcombinations of the reflectance and the reflectance difference, and thenumber of times of measurement thereof, and the like can be increased.However, it is possible to reduce the calculation load and to improvethe calculation speed, for example, by omitting the interpolationprocess.

On the other hand, for example, even though the colorimetric object 100is chromatic, in the case where the spectral reflectance is gentlychanged with respect to the change in wavelength in the colorimetricobject 100, the second deviation relating to the spectral sensitivitybetween the devices is small. Therefore, in such a case, by correctingthe first deviation relating to linearity with respect to the firstspectral reflectance R_(m)(λ) acquired by measurement using the firstspectrocolorimetric device 1 m in accordance with Mathematical Formula(3), the first spectral reflectance R_(m)(λ) can be converted to thesecond spectral reflectance R_(t)(λ).

[Mathematical Formula 3]

R _(t)(λ)≈R _(m)(λ)−ΔR(λ) . . .   (3)

FIG. 33 is a diagram exemplifying first and second spectral reflectancesR_(m)(λ) and R_(t)(λ) respectively acquired by measurement using thefirst and second spectrocolorimetric devices 1 m and 1 t. In FIG. 33,the first and second spectral reflectances R_(m)(λ) and R_(t)(λ)for thecolorimetric object 100 of which change in spectral reflectance withrespect to the change in wavelength λ is gentle are exemplified.

FIG. 34 is a diagram exemplifying the difference between the firstspectral reflectance R_(m)(λ) acquired by measurement using the firstspectrocolorimetric device 1 m and the second spectral reflectanceR_(t)(λ) acquired by measurement using the second spectrocolorimetricdevice 1 t for the colorimetric object 100 of which the spectralreflectance is gently changed with respect to a change in wavelength λ.As illustrated in FIG. 34, even when the colorimetric object 100 has agentle change in spectral reflectance with respect to a change inwavelength λ, the difference between the first spectral reflectanceR_(m)(λ) and the second spectral reflectance R_(t)(λ) occurs to someextent.

FIG. 35 is a diagram exemplifying a difference between a corrected firstspectral reflectance (first spectral reflectance R_(m)(λ)−ΔR) obtainedby subtracting the reflectance difference ΔR(λ) from the first spectralreflectance R_(m)(λ) and the second spectral reflectance R_(t)(λ)for thecolorimetric object 100 having a gentle change in spectral reflectancewith respect to a change in wavelength λ. Herein, the reflectancedifference ΔR(λ) is acquired by the acquisition unit 14 mb on the basisof the first spectral reflectance R_(m)(λ) relating to the colorimetricobject 100 and the relationship information A1. As illustrated in FIG.35, for the colorimetric object 100 having a gentle change in spectralreflectance with respect to a change in wavelength λ, if the firstdeviation relating to the linearity is corrected, a deviation inspectral reflectance between the first and second spectrocolorimetricdevices 1 m and 1 t can be sufficiently reduced.

In addition, as illustrated in FIG. 4, there are few colorimetricobjects 100 of which spectral reflectance is abruptly changed withrespect to a change in wavelength λ. For this reason, even though thesecond deviation relating to the spectral sensitivity is not corrected,if the first deviation relating to the linearity is corrected, in manycases, the deviation of spectral reflectance between the first andsecond spectrocolorimetric devices 1 m and 1 t is sufficiently reduced.

FIG. 36 is a flowchart illustrating an operation flow of setting therelationship information A1 as the first conversion rule for correctingthe first deviation relating to the linearity.

First, in step ST1, the spectral reflectance of each of the plurality ofsamples is measured by the first and second spectrocolorimetric devices1 m and 1 t. Herein, the plurality of samples are, for example, aplurality of achromatic calibration samples having different spectralreflectances. In the first spectrocolorimetric device 1 m, for example,with respect to each achromatic calibration sample, the spectroscopicspectrum relating to the reflected light from the colorimetric object100 is measured by the light-receiving unit 13, and the first spectralreflectance R_(m)(λ) of the colorimetric object 100 can be calculatedfrom the spectroscopic spectrum by the calculation unit 14 ma. Inaddition, in the second spectrocolorimetric device 1 t, for example,with respect to each achromatic calibration sample, the spectroscopicspectrum relating to reflected light from the colorimetric object 100 ismeasured to the light-receiving unit 13, and the second spectralreflectance R_(t)(λ) of the colorimetric object 100 can be calculatedfrom the spectroscopic spectrum by the calculation unit 14 ta.

Next, in step ST2, on the basis of the measurement result in step ST1,the arithmetic unit 14 md acquires the relationship between thereflectance for each wavelength and the reflectance difference as adeviation component relating to the reflectance between the plurality offirst spectral reflectances R_(m)(λ) and the plurality of secondspectral reflectances R_(t)(λ).

Next, in step ST3, the setting unit 14 me sets the relationshipinformation A1 as the first conversion rule. Herein, the relationshipinformation A1 is set as a first conversion rule that converts the firstspectral reflectance R_(m)(λ) to the second spectral reflectanceR_(t)(λ) on the basis of the relationship between the reflectance andthe reflectance difference for each wavelength acquired in step ST2.

By such an operation flow, the relationship between the reflectance andthe reflectance difference for each wavelength can be easily obtained.For this reason, a highly-accurate conversion rule of measurement valuesbetween the first and second spectrocolorimetric devices 1 m and 1 twhich are different from each other can be easily set.

As described above, the first spectral reflectance R_(m)(λ) is convertedinto the second spectral reflectance R_(t)(λ) that can be acquired bymeasurement using the second spectrocolorimetric device 1 t on the basisof the relationship between the reflectance and the reflectancedifference for each wavelength and the first spectral reflectanceR_(m)(λ) calculated from the spectroscopic spectrum acquired bymeasurement. Therefore, the first deviation relating to the linearitybetween the devices can be corrected. Then, herein, separately from thesecond deviation relating to the spectral sensitivity, the relationshipbetween the reflectance and the reflectance difference for eachwavelength is set. For this reason, a highly-accurate conversion rule ofmeasurement values between the first and second spectrocolorimetricdevices 1 m and 1 t which are different from each other can be easilyset.

<(1-4-2) Correction of Deviation (Second Deviation) Relating to SpectralSensitivity between Devices>

As illustrated in FIG. 4, in the case where the spectral reflectance ofthe colorimetric object 100 is abruptly changed with respect to a changein wavelength, the deviation in spectral reflectance due to the seconddeviation relating to the spectral sensitivity occurs. Therefore, if thesecond deviation relating to the spectral sensitivity between thedevices is corrected, the deviation in spectral reflectance between thedevices can be sufficiently reduced.

Herein, a method of correcting both of the first deviation relating tothe linearity between the devices and the second deviation relating tothe spectral sensitivity between the devices will be described. However,in the case where the optical systems or the like are not differentbetween the devices and the first deviation relating to the linearityhardly occurs, for example, the second deviation relating to thespectral sensitivity may be corrected without correcting the firstdeviation relating to the linearity between the devices.

An intensity (also referred to as a spectroscopic spectrum) of the lighthaving the wavelength λ of the incident light L0 incident from thecolorimetric object 100 through the slit portion 131 s into thelight-receiving unit 13 in the first spectrocolorimetric device 1 m isdenoted by L(λ). A spectral sensitivity of the k-th light-receivingelement (k is a natural number of 1 to K0) of the sensor unit 133 of thefirst spectrocolorimetric device 1 m is denoted by s_(m)(k,λ), and acenter wavelength of the light received by the k-th light-receivingelement is denoted by λ_(G) _(_) _(m)(k). At this time, an intermediatewavelength (also referred to as an intermediate wavelength) λ_(B) _(_)_(m)(k) between the center wavelength λ_(G) _(_) _(m)(k−1) of the lightreceived by the (k−1)-th light-receiving element and the centerwavelength λ_(G) _(_) _(m)(k) of the light received by the k-thlight-receiving element in the sensor unit 133 of the firstspectrocolorimetric device 1 m is represented by Mathematical Formula(4).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 4} \right\rbrack & \; \\{{\lambda_{B\_ m}(k)} = \frac{{\lambda_{G\_ m}\left( {k - 1} \right)} + {\lambda_{G\_ m}(k)}}{2}} & (4)\end{matrix}$

Then, a signal (also referred to as a first output signal) C_(m)(k)output according to the intensity of light at the k-th light-receivingelement in the sensor unit 133 of the first spectrocolorimetric device 1m is represented by Mathematical Formula (5).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 5} \right\rbrack & \; \\\begin{matrix}{{C_{m}(k)} = {\int_{0}^{\infty}{{{S_{m}\left( {k,\lambda} \right)} \cdot {L(\lambda)} \cdot \ d}\; \lambda}}} \\{\cong {\sum\limits_{j = 1}^{K_{0}}{{L\left( {\lambda_{G\_ m}(j)} \right)} \cdot {\int_{\lambda_{{B\_ m}{(j)}}}^{\lambda_{{B\_ m}{({j + 1})}}}{{{S_{m}\left( {k,\lambda} \right)}\  \cdot d}\; \lambda}}}}} \\{= {\sum\limits_{j = 1}^{K_{0}}{{L\left( {\lambda_{G\_ m}(j)} \right)} \cdot {S_{m}\left( {k,j} \right)}}}}\end{matrix} & (5)\end{matrix}$

Mathematical Formula (5) can be rewritten as a determinant asrepresented in Mathematical Formula (6).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 6} \right\rbrack & \; \\{{\begin{pmatrix}{C_{m}(1)} \\\vdots \\{C_{m}\left( K_{0} \right)}\end{pmatrix} = {\begin{pmatrix}{S_{m}\left( {1,1} \right)} & \ldots & {S_{m}\left( {1,K_{0}} \right)} \\\vdots & \ddots & \vdots \\{S_{m}\left( {K_{0},1} \right)} & \ldots & {S_{m}\left( {K_{0},K_{0}} \right)}\end{pmatrix} \cdot \begin{pmatrix}{L\left( {\lambda_{G\_ m}(1)} \right)} \\\vdots \\{L\left( {\lambda_{G\_ m}\left( K_{0} \right)} \right)}\end{pmatrix}}}{{{provided}\mspace{14mu} {that}},{{S_{m}\left( {k,j} \right)} = {\int_{\lambda_{B\_ m}{(j)}}^{\lambda_{B\_ m}{({j + 1})}}{{{S_{m}\left( {k,\lambda} \right)} \cdot \ d}\; \lambda}}}}} & (6)\end{matrix}$

Then, in the k-th light-receiving element in the sensor unit 133 of thefirst spectrocolorimetric device 1 m, the first output signal C_(m)(k)is output in response to the incidence of the incident light L0 havingthe spectroscopic spectrum L(λ). At this time, the light intensity (alsoreferred to as a first spectroscopic spectrum) L(λ_(G) _(_) _(m)(k)) atthe wavelength λ_(G) _(_) _(m)(k) of the incident light L0 is calculatedby inserting the first output signal C_(m)(k) into Mathematical Formula(7).

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 7} \right\rbrack} & \; \\{\begin{pmatrix}{L\left( {\lambda_{G\_ m}(1)} \right)} \\\vdots \\{L\left( {\lambda_{G\_ m}\left( K_{0} \right)} \right)}\end{pmatrix} = {\begin{pmatrix}{S_{m}\left( {1,1} \right)} & \ldots & {S_{m}\left( {1,K_{0}} \right)} \\\vdots & \ddots & \vdots \\{S_{m}\left( {K_{0},1} \right)} & \ldots & {S_{m}\left( {K_{0},K_{0}} \right)}\end{pmatrix}^{- 1} \cdot \begin{pmatrix}{C_{m}(1)} \\\vdots \\\left. {C_{m}\left( K_{0} \right)} \right)\end{pmatrix}}} & (7)\end{matrix}$

Herein, if an accurate spectral sensitivity s_(m)(k,λ) of the firstspectrocolorimetric device 1 m is obtained, the first spectroscopicspectrum L(λ_(G) _(_) _(m)(k)) relating to the incident light L0 isaccurately obtained by Mathematical Formula (7). For example, if thefirst spectrocolorimetric device 1 m is a product of a certainmanufacturer, the spectral sensitivity s_(m)(k,λ) at the light-receivingunit 13 of the first spectrocolorimetric device 1 m can be accuratelyobtained by the certain manufacturer. For example, in the case where theoutput signals from the light-receiving elements are directly obtainedin the first spectrocolorimetric device 1 m, the output signals outputfrom the light-receiving elements of the first spectrocolorimetricdevice 1 m according to the light of the specific wavelength may beobtained, so that the spectral sensitivity s_(m)(k,λ) may be calculated.Herein, as the light having the specific wavelength, for example, atleast one of monochromatic light emitted from the monochromator andlight having a plurality of specific wavelengths emitted from thebright-line light source may be employed.

In addition, herein, it is assumed that the incident light L0 having thesame spectroscopic spectrum L(λ) as the incident light on thelight-receiving unit 13 of the first spectrocolorimetric device 1 m isalso incident on the light-receiving unit 13 of the secondspectrocolorimetric device 1 t. In addition, a true spectral sensitivityof the k-th light-receiving element in the sensor unit 133 of the secondspectrocolorimetric device 1 t is denoted by s_(t)(k,λ), and a centerwavelength of light received by the k-th light-receiving element isdenoted by λ_(G) _(_) _(t)(k).

At this time, an intermediate wavelength (also referred to as anintermediate wavelength) λ_(B) _(_) _(t)(k) between the centerwavelength λ_(G) _(_) _(t)(k−1) of the light received by the (k−1)-thlight-receiving element in the sensor unit 133 and the center wavelengthof λ_(G) _(_) _(t)(k) of the light received by the k-th light-receivingelement is represented by Mathematical Formula (8).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 8} \right\rbrack & \; \\{{\lambda_{B\_ t}(k)} = \frac{{\lambda_{G\_ t}\left( {k - 1} \right)} + {\lambda_{G\_ t}(k)}}{2}} & (8)\end{matrix}$

Herein, the intensity L(λ_(G) _(_) _(t)(k)) of the incident light L0 atthe center wavelength λ_(G) _(_) _(t)(k) is obtained by an interpolationprocess using, for example, the intensity L(λ_(G) _(_) _(m)(k)) of theincident light L0 at two adjacent wavelengths λ_(G) _(_) _(m)(k)interposing the center wavelength λ_(G) _(_) _(t)(k).

In addition, in this case, for example, if the secondspectrocolorimetric device 1 t is a product of a certain manufacturer,the true spectral sensitivity s_(t)(k,λ) at the light-receiving unit 13of the second spectrocolorimetric device 1 t can be accurately obtainedby the certain manufacturer. For example, in the case where the outputsignals from the light-receiving elements are directly obtained in thesecond spectrocolorimetric device 1 t, the output signals output fromthe light-receiving elements of the second spectrocolorimetric device 1t according to the light of the specific wavelength are obtained, sothat the spectral sensitivity s_(t)(k,λ) may be obtained. Herein, as thelight having the specific wavelength, for example, at least one ofmonochromatic light emitted from the monochromator and light having aplurality of specific wavelengths emitted from the bright-line lightsource may be employed. In addition, the spectral sensitivity s_(t)(k,λ)may be obtained by, for example, optical simulation.

In addition, herein, it is assumed that the incident light L0 having thesame spectroscopic spectrum L(λ) as the incident light on thelight-receiving unit 13 of the first spectrocolorimetric device 1 m isincident on the light-receiving unit 13 of the secondspectrocolorimetric device 1 t. In this case, the estimated value (alsoreferred to as a second estimated output signal) C_(t)(k) of the outputsignal that can be output according to the intensity of light by thek-th light-receiving element in the sensor unit 133 of the secondspectrocolorimetric device 1 t can be calculated by Mathematical Formula(9).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 9} \right\rbrack & \; \\\begin{matrix}{{C_{t}(k)} = {\int_{0}^{\infty}{{{S_{t}\left( {k,\lambda} \right)} \cdot {L(\lambda)} \cdot \ d}\; \lambda}}} \\{\cong {\sum\limits_{j = 1}^{K_{0}}{{L\left( {\lambda_{G\_ t}(j)} \right)} \cdot {\int_{\lambda_{{B\_ t}{(j)}}}^{\lambda_{{B\_ t}{({j + 1})}}}{{{S_{t}\left( {k,\lambda} \right)}\  \cdot d}\; \lambda}}}}} \\{= {\sum\limits_{j = 1}^{K_{0}}{{L\left( {\lambda_{G\_ t}(j)} \right)} \cdot {S_{t}\left( {k,\lambda} \right)}}}}\end{matrix} & (9)\end{matrix}$

Mathematical Formula (9) can be rewritten as a determinant asrepresented in Mathematical Formula (10).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 10} \right\rbrack & \; \\{{\begin{pmatrix}{C_{t}(1)} \\\vdots \\{C_{t}\left( K_{0} \right)}\end{pmatrix} = {\begin{pmatrix}{S_{t}\left( {1,1} \right)} & \ldots & {S_{t}\left( {1,K_{0}} \right)} \\\vdots & \ddots & \vdots \\{S_{t}\left( {K_{0},1} \right)} & \ldots & {S_{t}\left( {K_{0},K_{0}} \right)}\end{pmatrix} \cdot \begin{pmatrix}{L\left( {\lambda_{G\_ t}(1)} \right)} \\\vdots \\{L\left( {\lambda_{G\_ t}\left( K_{0} \right)} \right)}\end{pmatrix}}}{{{provided}\mspace{14mu} {that}},{{S_{t}\left( {k,j} \right)} = {\int_{\lambda_{B\_ t}{(j)}}^{\lambda_{B\_ t}{({j + 1})}}{{{S_{t}\left( {k,\lambda} \right)} \cdot \ d}\; \lambda}}}}} & (10)\end{matrix}$

Herein, with respect to the k-th light-receiving element in the sensorunit 133 of the second spectrocolorimetric device 1 t, the calibratedspectral sensitivity (also referred to as a calibrated spectralsensitivity) obtained by calibration of the wavelength in the secondspectrocolorimetric device 1 t is denoted by s*_(t)(k,λ). In addition,at this time, the calibrated center wavelength (also referred to as acalibrated center wavelength) of light received by the k-thlight-receiving element is denoted by λ*_(G) _(_) _(t)(k). Thecalibrated spectral sensitivity s*_(t)(k,λ) may be a spectralsensitivity deviated from the true spectral sensitivity s_(t)(k,λ)depending on an accuracy of a wavelength calibration method in thesecond spectrocolorimetric device 1 t.

In addition, an intermediate wavelength (also referred to as acalibrated intermediate wavelength) λ*_(B) _(_) _(t)(k) between thecalibrated center wavelength λ*_(G) _(_) _(t)(k−1) of the light receivedby the (k−1)-th light-receiving element and the calibrated centerwavelength λ*_(G) _(_) _(t)(k) of the light received by the k-thlight-receiving element in the sensor unit 133 of the secondspectrocolorimetric device 1 t is represented by Mathematical Formula(11).

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 11} \right\rbrack & \; \\{{\lambda_{B\_ t}^{*}(k)} = \frac{{\lambda_{G\_ t}^{*}\left( {k - 1} \right)} + {\lambda_{G\_ t}^{*}(k)}}{2}} & (11)\end{matrix}$

By inserting the second estimated output signal C_(t)(k) obtained byMathematical Formula (10) into Mathematical Formula (12), the estimatedvalue (also referred to as a second estimated spectroscopic spectrum)L*(λ*_(G) _(_) _(t)(k)) of the calibrated strength of the incident lightL0 can be calculated.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 12} \right\rbrack} & \; \\{{\begin{pmatrix}{L^{*}\left( {\lambda_{G\_ t}^{*}(1)} \right)} \\\vdots \\{L^{*}\left( {\lambda_{G\_ t}^{*}\left( K_{0} \right)} \right)}\end{pmatrix} = {\begin{pmatrix}{S_{t}^{*}\left( {1,1} \right)} & \ldots & {S_{t}^{*}\left( {1,K_{0}} \right)} \\\vdots & \ddots & \vdots \\{S_{t}^{*}\left( {K_{0},1} \right)} & \ldots & {S_{t}^{*}\left( {K_{0},K_{0}} \right)}\end{pmatrix}^{- 1} \cdot \begin{pmatrix}{C_{t}(1)} \\\vdots \\\left. {C_{t}\left( K_{0} \right)} \right)\end{pmatrix}}}\mspace{20mu} {{{provided}\mspace{14mu} {that}},\mspace{20mu} {{S_{t}^{*}\left( {k,j} \right)} = {\int_{\lambda_{B\_ t}^{*}{(j)}}^{\lambda_{B\_ t}^{*}{({j + 1})}}{{{S_{t}^{*}\left( {k,\lambda} \right)} \cdot \ d}\; \lambda}}}}} & (12)\end{matrix}$

Namely, by sequentially performing the following Steps 1 to 3, thesecond estimated spectroscopic spectrum L*(λ*_(G) _(_) _(t)(k)) relatingto the incident light L0 can be acquired.

[Step 1] As represented in Mathematical Formula (7), the spectroscopicspectrum L(λ) of the incident light L0 is calculated by a product of theinverse matrix relating to the spectral sensitivity s_(m)(k,λ) and thecolumn vector of the output signal C_(m)(k) according to the incidentlight L0 acquired by actual measurement using the firstspectrocolorimetric device 1 m.

[Step 2] As represented in Mathematical Formula (10), the column vectorof the second estimated output signal C_(t)(k) that can be acquired bythe second spectrocolorimetric device 1 t is calculated by a product ofthe matrix relating to the true spectral sensitivity s_(t)(k,λ) of thesecond spectrocolorimetric device 1 t and the column vector of thespectroscopic spectrum L(λ) of the incident light L0 calculated in Step1. Herein, the second estimated output signal C_(t)(k) is an estimatedvalue of the output signal that is estimated to be acquired bymeasurement using the second spectrocolorimetric device 1 t when theincident light L0 is incident on the light-receiving unit 13 of thesecond spectrocolorimetric device 1 t. However, it is assumed that thespectroscopic spectrum L(λ) of the incident light L0 incident on thelight-receiving unit 13 of the second spectrocolorimetric device 1 t isthe same as the spectroscopic spectrum L(λ) of the incident light L0incident on the light-receiving unit 13 of the first spectrocolorimetricdevice 1 m.

[Step 3] As represented in Mathematical Formula (12), the secondestimated spectroscopic spectrum L*(λ*_(G) _(_) _(t)(k)) is calculatedby a product of the inverse matrix of the calibrated spectralsensitivity s*_(t)(k,λ) of the second spectrocolorimetric device 1 t andthe column vector of the second estimated output signal C_(t)(k)acquired in Step 2. The second estimated spectroscopic spectrumL*(λ*_(G) _(_) _(t)(k)) is an estimated value of the spectroscopicspectrum of the incident light L0 that can be acquired by measurementusing the second spectrocolorimetric device 1 t.

In addition, it is assumed that the incident light L0 having the samespectroscopic spectrum as the incident light L0 incident on thelight-receiving unit 13 of the first spectrocolorimetric device 1 m isincident on the light-receiving unit 13 of the secondspectrocolorimetric device 1 t. Therefore, the estimated value (alsoreferred to as the second estimated spectral reflectance) R*(λ*_(G) _(_)_(t)(k)) of the second spectral reflectance of the colorimetric object100 that can be acquired by measurement using the secondspectrocolorimetric device 1 t can be calculated by Mathematical Formula(13).

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 13} \right\rbrack} & \; \\{{R_{t}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right)} = {{\frac{{L_{Sample}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right)} - {L_{Black}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right)}}{{L_{White}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right)} - {L_{Black}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right)}} \times {R_{White}\left( {\lambda_{G\_ t}^{*}(k)} \right)}} - {\Delta \; {R\left( {\lambda_{G\_ t}^{*}(k)} \right)}}}} & (13)\end{matrix}$

In Mathematical Formula (13), the second estimated spectral reflectanceR*_(t)(λ*_(G) _(_) _(t)(k)) is represented as a value obtained bysubtracting the second term on the right hand side according to thefirst deviation relating to the linearity from the first term on theright hand side according to the second deviation relating to thespectral sensitivity. Herein, the first term on the right hand side ischanged according to the second deviation relating to the spectralsensitivity due to the accuracy of the wavelength calibration method inthe second spectrocolorimetric device 1 t. In addition, the second termon the right hand side indicates the reflectance difference ΔR(λ*_(G)_(_) _(t)(k)) as the first deviation relating to the linearity in thespectral reflectance.

Herein, with respect to the first term on the right hand side ofMathematical Formula (13), L*_(White)(λ*_(G) _(_) _(t)(k)) is a secondestimated spectroscopic spectrum (also referred to as a second whiteestimated spectroscopic spectrum) relating to the white calibrationplate. L*_(Black)(λ*_(G) _(_) _(t)(k)) is the second estimatedspectroscopic spectrum (also referred to as second black estimatedspectroscopic spectrum) relating to the black calibration plate.L*_(Sample)(λ*_(G) _(_) _(t)(k)) is a second estimated spectroscopicspectrum (also referred to as a second object estimated spectroscopicspectrum) relating to the colorimetric object 100. In addition,R_(White)(λ*_(G) _(_) _(t)(k)) is a second spectral reflectance (alsoreferred to as a second white spectral reflectance) relating to thewhite calibration plate.

The second white estimated spectroscopic spectrum L*_(White)(λ*_(G) _(_)_(t)(k)), the second black estimated spectroscopic spectrumL*_(Black)(λ*_(G) _(_) _(t)(k)), and the second object estimatedspectroscopic spectrum L*_(Sample)(λ*_(G) _(_) _(t)(k)) can becalculated, for example, by performing the measurement and calculationaccording to the above-described Steps 1 to 3 with respect to the whitecalibration plate, the black calibration plate, and the colorimetricobject 100. Specifically, with respect to the white calibration plate,the second white estimated spectroscopic spectrum L*_(White)(λ*_(G) _(_)_(t)(k)) is calculated on the basis of the first output signal C_(m)(k)obtained by actual measurement using the first spectrocolorimetricdevice 1 m and Mathematical Formulas (7), (10), and (12). With respectto the black calibration plate, the second black estimated spectroscopicspectrum L*_(Black)(λ*_(G) _(_) _(t)(k)) is calculated on the basis ofthe first output signal C_(m)(k) obtained by actual measurement usingthe first spectrocolorimetric device 1 m and Mathematical Formulas (7),(10), and (12). The second object estimated spectroscopic spectrumL*_(Sample)(λ*_(G) _(_) _(t)(k)) is calculated by the first outputsignal C_(m)(k) obtained by the actual measurement using the firstspectrocolorimetric device 1 m for the colorimetric object 100 andMathematical Formulas (7), (10) and (12).

For example, the second white spectral reflectance R_(White)(λ*_(G) _(_)_(t)(k)) may be preset for the white calibration plate.

In addition, the reflectance difference ΔR(λ*_(G) _(_) _(t)(k)) of thesecond term on the right hand side of Mathematical Formula (13) can beacquired by, for example, using the method described in Section (1-4-1)on the basis of the first spectral reflectance R_(m)(λ*_(G) _(_)_(t)(k)) acquired by measurement using the first spectrocolorimetricdevice 1 m for the colorimetric object 100 and the relationshipinformation A1. In addition, the relationship information A1 can also beset, for example, by the method described in the above Section (1-4-1).

The first spectral reflectance R_(m)(λ*_(G) _(_) _(t)(k)) can becalculated by Mathematical Formula (14).

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 14} \right\rbrack} & \; \\{{R_{m}\left( {\lambda_{G\_ t}^{*}(k)} \right)} = {\frac{{L_{Sample}\left( {\lambda_{G\_ t}^{*}(k)} \right)} - {L_{Black}\left( {\lambda_{G\_ t}^{*}(k)} \right)}}{{L_{White}\left( {\lambda_{G\_ t}^{*}(k)} \right)} - {L_{Black}\left( {\lambda_{G\_ t}^{*}(k)} \right)}} \times {R_{White}\left( {\lambda_{G\_ t}^{*}(k)} \right)}}} & (14)\end{matrix}$

In Mathematical Formula (14), L_(White)(λ*_(G) _(_) _(t)(k)) is aspectroscopic spectrum (also referred to as a second white spectroscopicspectrum) that can be acquired by measurement using the secondspectrocolorimetric device 1 t for the white calibration plate.L_(Black)(λ*_(G) _(_) _(t)(k)) is a spectroscopic spectrum (alsoreferred to as a second black spectroscopic spectrum) that can beacquired by measurement using the second spectrocolorimetric device 1 twith respect to the black calibration plate. L_(Sample)(λ*_(G) _(_)_(t)(k)) is a spectroscopic spectrum (also referred to as a secondobject spectroscopic spectrum) that can be acquired by measurement usingthe second spectrocolorimetric device 1 t for the colorimetric object100. In addition, R_(White)(λ*_(G) _(_) _(t)(k)) is the second spectralreflectance (second white spectral reflectance) relating to the whitecalibration plate. In addition, herein, the spectral reflectance of theblack calibration plate is treated as 0%.

Herein, for example, the spectroscopic spectrum (also referred to as afirst white spectroscopic spectrum) L_(White)(λ_(G) _(_) _(m)(k))relating to the white calibration plate can be acquired by applying thefirst output signal C_(m)(k) acquired by measurement using the firstspectrocolorimetric device 1 m for the white calibration plate toMathematical Formula (7). Then, the second white spectroscopic spectrumL_(White)(λ*_(G) _(_) _(t)(k)) can be acquired by interpolationoperation of the first white spectroscopic spectrum L_(White)(λ_(G) _(_)_(m)(k)).

In addition, for example, the spectroscopic spectrum (also referred toas a first black spectroscopic spectrum) L_(Black)(λ_(G) _(_) _(m)(k))of the black calibration plate can be obtained by applying the firstoutput signal C_(m)(k) acquired by measurement using the firstspectrocolorimetric device 1 m for the black calibration plate toMathematical Formula (7). Then, the second black spectroscopic spectrumL_(Black)(λ*_(G) _(_) _(t)(k)) can be acquired by an interpolationoperation of the first black spectroscopic spectrum L_(Black)(λ_(G) _(_)_(m)(k)).

In addition, for example, the spectroscopic spectrum (also referred toas a first object spectroscopic spectrum) L_(Sample)(α_(G) _(_) _(m)(k))of the colorimetric object 100 can be obtained by applying the firstoutput signal C_(m)(k) acquired by measurement using the firstspectrocolorimetric device 1 m for the colorimetric object 100 toMathematical Formula (7). Then, the second object spectroscopic spectrumL_(Sample)(λ*_(G) _(_) _(t)(k)) can be acquired by the interpolationoperation of the first object spectroscopic spectrum L_(Sample)(λ_(G)_(_) _(m)(k)).

On the other hand, in some cases, the second estimated spectralreflectance R*(λ*_(G) _(_) _(t)(k)) represented by Mathematical Formula(13) may be deviated from the actually measured value (also referred toas the second measured spectral reflectance) R(λ*_(G) _(_) _(t)(k)) ofthe second spectral reflectance calculated from the spectroscopicspectrum L(λ*_(G) _(_) _(t)(k)) obtained by actual measurement using thesecond spectrocolorimetric device 1 t. The difference between the secondestimated spectral reflectance R*(λ*_(G) _(_) _(t)(k)) and the secondmeasured spectral reflectance R(λ*_(G) _(_) _(t)(k) is estimated to becaused by the accuracy of wavelength calibration in the secondspectrocolorimetric device 1 t.

Therefore, the calibrated spectral sensitivity s*_(t)(k,λ) in the secondspectrocolorimetric device 1 t is adjusted so as to minimize thedifference between the second measured spectral reflectance R(λ*_(G)_(_) _(t)(k)) and the second estimated spectral reflectance R*(λ*_(G)_(_) _(t)(k)).

Specifically, the calibrated spectral sensitivity s*_(t)(k,λ) that isprovisionally set when the objective function F represented byMathematical Formula (15) is included in a minimum region is estimatedto be the calibrated spectral sensitivity s*_(t)(k,λ) relating to thesecond spectrocolorimetric device 1 t.

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 15} \right\rbrack & \; \\{F = {\sum\limits_{n = 1}^{N_{0}}{\sum\limits_{k = 1}^{K_{0}}\left( {{R_{t}\left\{ {\lambda_{G\_ t}^{*}(k)} \right)} - {R_{t}^{*}\left( {\lambda_{G\_ t}^{*}(k)} \right\}}} \right)^{2}}}} & (15)\end{matrix}$

Herein, the objective function F in Mathematical Formula (15) representsa summation of squares of differences between the second measuredspectral reflectance R(λ_(G) _(_) _(t)(k)) and the second estimatedspectral reflectance R*(λ_(G) _(_) _(t)(k)) which are obtained for N₀(N₀ is a natural number) samples. When the objective function F isincluded in the minimum region, the second estimated spectralreflectance R*(λ_(G) _(_) _(t)(k)) is matched with the second measuredspectral reflectance R(λ_(G) _(_) _(t)((k)). In addition, the state thatthe objective function F is included in the minimum region includes, forexample, a state that the objective function F has a minimum value, astate that the objective function F has a value in the vicinity of theminimum value, and the like. The state that the objective function F hasa value in the vicinity of the minimum value includes, for example, astate that, after the change of the objective function F is coarselygrasped, the objective function F is changed only by a presetpredetermined value or less in slope in the vicinity of the minimumvalue. In addition, for example, a state that the difference between thesecond estimated spectral reflectance R*(λ_(G) _(_) _(t)(k)) and thesecond measured spectral reflectance R(λ_(G) _(_) _(t)(k)) is includedwithin a preset predetermined allowable range in which a colordifference is about 0.1 or less may be the state that the objectivefunction F is included in the minimum region.

If each of the N₀ samples exhibits a spectral reflectance in which theamount of change in the reflectance with respect to the change in thepredetermined amount of wavelength exceeds a preset threshold value inthe to-be-measured wavelength range, the second estimated spectralreflectance R*(λ_(G) _(_) _(t)(k)) can be matched to the second measuredspectral reflectance R(λ_(G) _(_) _(t)(k)). Namely, the calibratedspectral sensitivity s*_(t)(k,λ) can be easily and accurately set.

FIG. 37 is a diagram exemplifying the spectral reflectance of N₀calibration samples used for matching. If the entire to-be-measuredwavelength range is covered by a region where the spectral reflectancegreatly changes in any of the N₀ calibration samples, the secondestimated spectral reflectance R*(λ_(G) _(_) _(t)(k)) is accuratelymatched to the second measured spectral reflectance R(λ_(G) _(_)_(t)(k)) in the entire to-be-measured wavelength range.

As illustrated in FIG. 37, if a plurality of calibration samples, forexample, about five (N₀=5) calibration samples are used, the secondestimated spectral reflectance R*(λ_(G) _(_) _(t)(k)) can be accuratelymatched to the second measured spectral reflectance R(λ_(G) _(_)_(t)(k)) in the entire to-be-measured wavelength range of visible light.If the colorimetric object 100 is an object of a specific color, forexample, one or more calibration samples of which spectral reflectancechanges greatly in the wavelength range corresponding to the specificcolor may be used.

On the other hand, in order to allow the objective function F to beincluded in the minimum region, for example, while changing thecalibrated spectral sensitivity s*_(t)(k,λ), it is necessary to obtainthe objective function F of each provisional calibrated spectralsensitivity s*_(t)(k,λ).

Herein, it is assumed that the calibrated spectral sensitivitys*_(t)(k,λ) obtained by wavelength calibration in the secondspectrocolorimetric device 1 t for the k-th light-receiving element inthe sensor unit 133 is a normal distribution function defined by thecenter wavelength λ*_(G) _(_) _(t)(k) represented by the L-th orderfunction of Mathematical Formula (16) and the full width at half maximumΔλ*_(FWHM)(k) represented by the L-th order function of MathematicalFormula (17). In addition, the order L may be, for example, a naturalnumber of 2 or more.

[Mathematical Formula 16]

λ*_(G) _(_) _(t)(k)=a _(L) ·k ^(L) +. . . +a ₀ . . .   (16)

[Mathematical Formula 17]

Δλ*_(FWHM)(k)=b _(L) ·k ^(L) +. . . +b ₀. . .   (17)

FIG. 38 is a diagram illustrating an example of the spectral sensitivityof the k-th light-receiving element.

In this case, in order to allow the objective function F defined byMathematical Formula (15) to be included in the minimum region, forexample, the coefficients a_(L), . . . , a₀ of Mathematical Formula (16)and the coefficients b_(L), . . . , b₀ of Mathematical Formula (17) maybe obtained so that the objective function F is included in the minimumregion. Specifically, for example, if L=2, six coefficients a₂, a₁, a₀,b₂, b₁, and b₀ may be obtained. Then, if data based on the output fromthe light-receiving element at every 10 nm of 360 to 740 nm is obtainedfor one calibration sample, 195 points of data can be obtained for thefive calibration samples. Of these, if there are a considerable numberof data for the portion where the reflectance of the calibration sampleis greatly changed, the values of the six coefficients a₂, a₁, a₀, b₂b₁, and b₀ of Mathematical Formulas (16) and (17) can be easilyobtained.

From the above description, the second estimated spectral reflectanceR*(λ_(G) _(_) _(t)(k)) is estimated from the first output signalC_(m)(k) acquired by the first spectrocolorimetric device 1m by thefollowing Steps i to v. Then, the following Steps i to v are repeated,and thus, the calibrated spectral sensitivity s*_(t)(k,λ) of the secondspectrocolorimetric device 1 t is obtained so that the second estimatedspectral reflectance R*(λ_(G) _(_) _(t)(k)) and the second measuredspectral reflectance R(λ_(G) _(_) _(t)(k)) obtained by actualmeasurement using the second spectrocolorimetric device 1 t are close toeach other while the difference therebetween is included in the minimumregion. Herein, the second estimated spectral reflectance R*(λ_(G) _(_)_(t)(k)) is calculated by using the spectroscopic spectrum measured bythe light-receiving unit 13 of the first spectrocolorimetric device 1 mfor a calibration sample as one or more objects and the provisionalcalibrated spectral sensitivity s*_(t)(k,λ). In addition, the secondmeasured spectral reflectance R(λ_(G) _(_) _(t)(k)) is an actualmeasurement value of the spectral reflectance measured by the secondspectrocolorimetric device 1 t for the calibration sample as one or moreobjects. Then, the information indicating the calibrated spectralsensitivity s*_(t)(k,λ) obtained herein is stored in the storage unit 15as the calibrated spectral sensitivity information S1.

[Step i] The center wavelength λ*_(G) _(_) _(t)(k) and the full width athalf maximum Δλ*_(FWHM)(k) that define the calibrated spectralsensitivity s*_(t)(k,λ) of the k-th light-receiving element of thesecond spectrocolorimetric device 1 t are provisionally determined. Atthis time, the coefficients a_(L), . . . , a₀ of Mathematical Formula(16) and the coefficients b_(L), . . . , b₀ of Mathematical Formula (17)are provisionally determined. Accordingly, the inverse matrix of thecalibrated spectral sensitivity s*_(t)(k,λ) of Mathematical Formula (12)is provisionally determined.

[Step ii] The luminance (first spectroscopic spectrum) L(λ_(G) _(_)_(m)(k)) of the calibration sample is calculated on the basis of thefirst output signal C_(m)(k) acquired by the first spectrocolorimetricdevice 1 m and Mathematical Formula (7).

[Step iii] The second estimated output signal C_(t)(k) that can beacquired by the second spectrocolorimetric device 1 t is calculated byMathematical Formula (10) on the basis of the first spectroscopicspectrum L(λ_(G) _(_) _(m)(k)) obtained in Step ii, while the wavelengthis being interpolated.

[Step iv] The second estimated spectroscopic spectrum L*(λ_(G) _(_)_(t)(k)) is calculated on the basis of the second estimated outputsignal C_(t)(k) calculated in Step iii and Mathematical Formula (12)using the calibrated spectral sensitivity s*_(t)(k,λ) provisionallydetermined in Step i.

[Step v] The second estimated spectral reflectance R*_(t)(λ_(G) _(_)_(t)(k)) is calculated on the basis of the second estimatedspectroscopic spectrum L*(λ_(G) _(_) _(t)(k)) calculated in Step iv andMathematical Formula (13).

In this manner, the calibrated spectral sensitivity information S1defining the second conversion rule for correcting the second deviationrelating to the spectral sensitivity in order to convert the firstspectral reflectance R_(m)(λ) to the second spectral reflectanceR_(t)(λ) is set. Namely, in the case where such a configuration isemployed, the deviation between the first spectral reflectance and thesecond spectral reflectance is treated to be divided into the firstdeviation relating to the linearity and the second deviation relating tothe spectral sensitivity, and the second conversion rule is set by usinglimited calculation such as Mathematical Formulas (7), (10), (12), (13),and the like. Therefore, the second conversion rule can be set by usinga relatively small number of calibration samples. Namely, ahighly-accurate conversion rule of measurement values between thedifferent first and second spectrocolorimetric devices 1 m and 1 t canbe easily set.

Then, the second estimated spectral reflectance R*_(t)(λ_(G) _(_)_(t)(k)) that is estimated to be acquired by the secondspectrocolorimetric device 1 t can be calculated by using the firstspectroscopic spectrum measured by the light-receiving unit 13 of thefirst spectrocolorimetric device 1 m and the calibrated spectralsensitivity as the second conversion rule.

FIG. 39 is a flowchart illustrating an operation flow of correcting thesecond deviation relating to the spectral sensitivity.

First, in step ST11, the light-receiving unit 13 of the firstspectrocolorimetric device 1m spectroscopically disperses the reflectedlight generated on the surface of the colorimetric object 100 accordingto the irradiation of the colorimetric object 100 with the illuminationlight emitted from the light source 11, so that the first spectroscopicspectrum L(λ_(G) _(_) _(m)(k)) of the reflected light is measured.Herein, for example, the calculation unit 14 ma calculates the firstspectroscopic spectrum L(λ_(G) _(_) _(m)(k)) of the colorimetric object100 on the basis of the first output signal C_(m)(k) acquired by thefirst spectrocolorimetric device 1 m for the colorimetric object 100.

Next, in step ST12, the conversion unit 14 mc of the firstspectrocolorimetric device 1 m calculates the second estimated spectralreflectance R*_(t)(λ_(G) _(_) _(t)(k)) that can be acquired by thesecond spectrocolorimetric device 1 t. Herein, for example, the secondestimated spectral reflectance R*_(t)(λ_(G) _(_) _(t)(k)) is calculatedfrom the first spectroscopic spectrum L(λ_(G) _(_) _(m)(k)) by using thecalibrated spectral sensitivity information S1 stored in the storageunit 15 and the first spectroscopic spectrum L(λ_(G) _(_) _(m)(k))measured in step ST11.

In the case where such a configuration is employed, since the calibratedspectral sensitivity for the second deviation relating to the spectralsensitivity is set separately from the first deviation relating to thereflectance, a highly-accurate conversion rule of measurement valuesbetween the different first and second spectrocolorimetric devices 1 mand 1 t can be easily set.

(2) MODIFIED EXAMPLE

In addition, the present invention is not limited to the above-describedembodiment, and various modifications, improvements, and the like can bemade without departing from the spirit of the present invention.

For example, in the above-described embodiment, in order to set therelationship information A1 for correcting the first deviation relatingto the linearity between the devices, as an colorimetric object 100having spectral reflectance, of which reflectance is substantiallyconstant irrespective of the wavelength of the light, an achromaticcalibration sample is used, but the present invention is not limitedthereto. For example, at least a portion of the plurality of achromaticcalibration samples having different spectral reflectances from eachother may be replaced with a chromatic calibration sample of whichreflectance is included within a width of the predetermined value rangein a portion of the to-be-measured wavelength range to be measured bythe first spectrocolorimetric device 1 m. Namely, for example, a modemay be employed where all of the plurality of calibration samples usedfor setting the relationship information A1 for correcting the firstdeviation relating to the linearity between the devices are calibrationsamples of which reflectance is included within a width of apredetermined value range in a portion of the to-be-measured wavelengthrange. At this time, for example, among the plurality of calibrationsamples, all the calibration samples may be achromatic, some calibrationsamples may be achromatic, or all the calibration samples may not beachromatic.

In the case where such a mode is employed, a plurality of calibrationsamples for obtaining the relationship between the reflectance and thereflectance difference for each wavelength can be easily prepared.Therefore, the relationship between the reflectance and the reflectancedifference for each wavelength can be easily obtained.

In addition, the plurality of calibration samples employed for settingthe relationship information A1 may include different calibrationsamples of which the reflectances in at least a portion of theto-be-measured wavelength range are within a width of a presetpredetermined value range. However, in the case of employing such aconfiguration, for a calibration sample of which reflectance is includedwithin a width of a preset predetermined value range only in a portionof the to-be-measured wavelength range can be employed to obtain therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) for the portion of the wavelength range.For example, with respect to the red calibration sample illustrated inFIG. 4, the spectral reflectance can be substantially constant within awidth of the predetermined value range in the range of 550 nm or less inthe to-be-measured wavelength range. Therefore, the red calibrationsample may be employed as a calibration sample to obtain therelationship between the first spectral reflectance R_(m)(λ) and thereflectance difference ΔR(λ) in the range of 550 nm or less. Even in thecase where such a configuration is employed, the relationship betweenthe first spectral reflectance R_(m)(λ) and the reflectance differenceΔR(λ) as a deviation component relating to the first spectralreflectance R_(m)(λ) for each wavelength is easily acquired. Namely, ahighly-accurate conversion rule of measurement values between thedifferent first and second spectrocolorimetric devices 1 m and 1 t canbe more easily set.

In addition, in the above-described embodiment, the case where, due to adifference in optical system such as retroreflection by the transparentmember 17 t between the first and second spectrocolorimetric devices 1 mand 1 t, the reflectance difference can be generated between the firstspectral reflectance R_(m)(λ) and the second spectral reflectanceR_(t)(λ)is exemplified, but the present invention is not limitedthereto. For example, the method of correcting the first deviationrelating to the linearity according to the above-described embodimentmay also be applied to the correction of the first deviation relating tothe linearity caused by the deviation of the relationship between theamount of incident light and the output due to the difference in thecharacteristics of the light-receiving element of the light-receivingunit 13, the amplifier circuit, and the like between the first andsecond spectrocolorimetric devices 1 m and 1 t.

FIG. 40 is a diagram exemplifying the relationship between the amount ofincident light and the intensity of an output signal in each of thefirst and second spectrocolorimetric devices 1 m and 1 t. In FIG. 40,the relationship between the amount of incident light and the intensityof an output signal in the first spectrocolorimetric device 1 m is drawnby a solid line, and the relationship between the amount of incidentlight and the intensity of an output signal in the secondspectrocolorimetric device 1 t is drawn by a broken line.

In addition, in the above-described embodiment, the first and secondspectrocolorimetric devices 1 m and 1 t are different types of devices,but the present invention is not limited thereto. For example, the firstand second spectrocolorimetric devices 1 m and 1 t may be differentdevices of the same model. In other words, the method of correcting thefirst deviation relating to the linearity in the above-describedembodiment may also be applied to the correction of the first deviationrelating to the linearity occurring between the first and secondspectrocolorimetric devices 1 m and 1 t, which are different devices ofthe same model.

For example, as illustrated in FIG. 41, the case is assumed where, thefirst spectrocolorimetric device 1 m is also provided with a transparentmember 17 m having the same configuration and function as thetransparent member 17 t in the second spectrocolorimetric device 1 t andthe first spectrocolorimetric device 1 m and the secondspectrocolorimetric device 1 t are different devices of the same model.In this case, as illustrated in FIG. 42, the spectral reflectance can bedifferent between the transparent member 17 m and the transparent member17 t. In FIG. 42, for example, the spectral reflectance in thetransparent member 17 m is indicated by a solid line and the spectralreflectance in the transparent member 17 t is indicated by a brokenline. Namely, the spectral reflectances of the transparent members 17 mand 17 t or the like can have deviation for each of the transparentmembers 17 m and 17 t. As a result, the mode of retroreflection may bedifferent between the first and second spectrocolorimetric devices 1 mand 1 t. As a result, with respect to the same colorimetric object 100,a deviation may occur between the first spectral reflectance R_(m)(λ)acquired by measurement using the first spectrocolorimetric device 1 mand the second spectral reflectance R_(t)(λ) acquired by measurementusing the second spectrocolorimetric device 1 t.

In addition, in the above-described embodiment, for example, thecorrection of the second deviation relating to the spectral sensitivityis described by using 14 formulas of Mathematical Formulas (4) to (17),but the present invention is not limited thereto. For example, at leasta portion of 14 Mathematical Formulas (4) to (17) may be integrated ordecomposed as appropriate to obtain one or more formulas. In addition,if the first and second spectrocolorimetric devices 1 m and 1 t areproduced by the same manufacturer and the manufacturer has informationon the wavelength calibration of each device, such a configuration maybe employed where the second estimated spectral reflectance iscalculated on the basis of the data obtained by the firstspectrocolorimetric device 1 m and the information relating to thewavelength calibration of the second spectrocolorimetric device 1 t andthe calibrated spectral sensitivity s*_(t)(k,λ) is obtained so that thesummation of squares of differences between the second estimatedspectral reflectance and the second measured spectral reflectanceobtained by actual measurement using the second spectrocolorimetricdevice 1 t is minimized

In addition, in the above-described embodiment, the calibrated spectralsensitivity s*_(t)(k,λ) is a normal distribution function defined by acenter wavelength λ*_(G) _(_) _(t)(k) indicated by an L-th orderfunction represented by Mathematical Formula (16) and a full width athalf maximum Δλ*_(FWHM)(k) indicated by an L-th order functionrepresented by Mathematical Formula (17), but the present invention isnot limited thereto. For example, the calibrated spectral sensitivitys*_(t)(k,λ) may be represented by a different formula such as a formularepresenting the calibrated spectral sensitivity by appropriatelyshifting the reference formula.

In addition, in the above-described embodiment, the true spectralsensitivity s_(m)(k,λ) in the first spectrocolorimetric device 1 m andthe true spectral sensitivity s_(t)(k,λ) in the secondspectrocolorimetric device 1 t are accurately acquired, but the presentinvention is not limited thereto. For example, even though some erroroccurs between the spectral sensitivity acquired by measurement using abright-line light source or the like and the true spectral sensitivitys_(m)(k,λ) or s_(t)(k,λ), the objective function F defined byMathematical Formula (15) is allowed to be included in the minimumregion and the calibrated spectral sensitivity s*_(t)(k,λ) iscalculated, so that the influence due to the slight error can bereduced. For this reason, even in the case where the firstspectrocolorimetric device 1 m is a product of a certain manufacturerand the second spectrocolorimetric device 1 t is a product of anothermanufacturer, the calibrated spectral sensitivity information S1defining the second conversion rule can be set at a good accuracy.

In addition, in the above-described embodiment, the coefficients a_(L),. . . , a₀ of Mathematical Formula (16) and the coefficients b_(L), . .. , b₀ of Mathematical Formula (17) are adjusted so that the objectivefunction F of Mathematical Formula (15) is included in the minimumregion, but the present invention is not limited thereto. For example,if the first and second spectrocolorimetric devices 1 m and 1 t areproducts of the same manufacturer and, in the manufacturer of the firstand second spectrocolorimetric devices 1 m and 1 t, the true spectralsensitivity s_(m)(k,λ) in the first spectrocolorimetric device 1 m andthe true spectral sensitivity s_(t)(k,λ) in the secondspectrocolorimetric device 1 t are known, the calibrated spectralsensitivity s*_(t)(k,λ) determined by the calibration at the factory ofthe second spectrocolorimetric device 1 t may be employed as the secondconversion rule without changing the calibrated spectral sensitivity.

The “calibration at the factory” referred to herein may obtain, forexample, the coefficients a_(L), . . . , a₀ of Mathematical Formula (16)and the coefficients b_(L), . . . , b₀ of Mathematical Formula (17) thatdefine the calibrated spectral sensitivity s*_(t)(k,λ). Herein, thecalibration at the factory can be performed in various methods.Specifically, for example, the coefficients a_(L), . . . , a₀ and b_(L),. . . , b₀ are set so that the measurement value of the spectroscopicspectrum acquired by measurement using the second spectrocolorimetricdevice 1 t for monochromatic light having a very narrow full width athalf maximum of a wavelength emitted from a bright-line light source orthe like coincides with the spectroscopic spectrum of an actualmonochromatic light. Namely, the calibrated spectral sensitivitys*_(t)(k,λ) is set as the calibration result.

In the case where such a configuration is employed, first, the firstspectroscopic spectrum L(λ_(G) _(_) _(m)(k)) is calculated from thefirst output signal C_(m)(k) acquired by the first spectrocolorimetricdevice 1 m for the colorimetric object 100 by Mathematical Formula (7).Next, by applying the first spectroscopic spectrum L(λ_(G) _(_) _(m)(k))and the spectral sensitivity s_(t)(k,λ) to Mathematical Formula (10),the second estimated output signal C_(t)(k) which can be acquired by thesecond spectrocolorimetric device 1 t is calculated. Next, by applyingthe inverse matrix of the second estimated output signal C_(t)(k) andthe calibrated spectral sensitivity s*_(t)(k,λ) as the calibrationresult to Mathematical Formula (12), the second estimated spectroscopicspectrum L*(λ_(G) _(_) _(t)(k)) is calculated. Then, the secondestimated spectral reflectance R*(λ_(G) _(_) _(t)(k)) can be calculatedby applying the second estimated spectroscopic spectrum L*(λ_(G) _(_)_(t)(k)) to Mathematical Formula (13). Then, the calculation forallowing the objective function F to be included in the minimum regionis unnecessary.

In addition, in the above-described embodiment, it is assumed that thespectroscopic spectrum of the irradiation light emitted from the lightsource 11 is constant, but the present invention is not limited thereto.For example, it is assumed that the spectroscopic spectrum of theirradiation light changes as time elapses. In this case, in the firstspectrocolorimetric device 1 m, the irradiation light may be directlyreceived to acquire the output signal for reference, the output signalsobtained with respect to the colorimetric object 100, the whitecalibration plate, and the black calibration plate may be divided by theacquired output signal for reference, and then, the spectral reflectancemay be calculated by Mathematical Formulas (13), (14), or the like.

In addition, in the above-described embodiment, it is assumed that therelationship information A1 and the calibrated spectral sensitivityinformation S1 are set on the manufacturer side, but the presentinvention is not limited thereto. For example, on the user side, therelationship information A1 and the calibrated spectral sensitivityinformation S1 may be set. At this time, on the user side, the first andsecond spectrocolorimetric devices 1 m and 1 t, the plurality ofachromatic calibration samples for correcting the first deviationrelating to the linearity, and one or more chromatic calibration samplesfor correcting the second deviation relating to the spectral sensitivityare used. Specifically, for example, on the user side, measurement maybe performed using the first and second spectrocolorimetric devices 1 mand 1 t for a plurality of achromatic calibration samples and one ormore chromatic calibration samples, and the information obtained as aresult may be described in the storage unit 15 as the relationshipinformation A1 and the calibrated spectral sensitivity information S1.Accordingly, since the relationship information A1 and the calibratedspectral sensitivity information S1 are set by using the secondspectrocolorimetric device 1 t owned by the user, a highly-accurateconversion rule of the measurement value between the different first andsecond spectrocolorimetric devices 1 m and 1 t can be set.

In addition, in the above-described embodiment, in FIG. 1, FIG. 2 andFIG. 41, the configuration of 45/0 (45° illumination and verticalreception) recommended by the International Commission on Illumination(CIE) or the configuration of 0/45 (vertical illumination and 45°reception) recommended by the CIE has been employed, but the presentinvention is not limited thereto. For example, in the first and secondspectrocolorimetric devices 1 m and 1 t, for example, otherconfigurations such as a configuration where an integration sphere isprovided between the light source 11, the opening 2 o, and thelight-receiving unit 13 may be employed.

All or a portion of the above-described embodiment and various modifiedexamples can be combined as appropriate within a range withoutinconsistency.

REFERENCE SIGNS LIST

-   1 m First spectrocolorimetric device-   1 t Second spectrocolorimetric device-   2 Housing-   2 o Opening-   11 Light source-   12 Light-emitting circuit-   13 Light-receiving unit-   14 Control unit-   14 ma. 14 ta Calculation unit-   14 mb Acquisition unit-   14 mc Conversion unit-   14 md Arithmetic unit-   14 me Setting unit-   15 Storage unit-   16 Input/output unit-   17 m, 17 t Transparent member-   100 Colorimetric object-   131 Slit plate-   132 Spectroscopic unit-   133 Sensor unit-   A1 Relationship information-   S1 Calibrated spectral sensitivity information-   L0 Incident light-   M0 Memory-   P0 Processor-   P1, P2 Program

1. A spectrocolorimetric device comprising: a light source; alight-receiver which spectroscopically disperses reflected lightgenerated on a surface of an object according to irradiation of theobject with illumination light emitted from the light source andmeasures a spectroscopic spectrum relating to the reflected light; acalculator which calculates a first spectral reflectance from thespectroscopic spectrum; a storage which stores relationship informationindicating a relationship between a reflectance and a reflectancedifference as a deviation component of reflectance for each wavelength;an acquirer which acquires reflectance difference for each wavelengthbetween the first spectral reflectance acquired by measurement using thespectrocolorimetric device and a second spectral reflectance that can beacquired by measurement using a destination-of-conversionspectrocolorimetric device different from the spectrocolorimetric deviceon the basis of the first spectral reflectance and the relationshipinformation; and a converter which converts the first spectralreflectance into the second spectral reflectance by adding orsubtracting the reflectance difference for each wavelength acquired bythe unit acquirer to or from the first spectral reflectance.
 2. Thespectrocolorimetric device according to claim 1, wherein therelationship information includes a relational formula representing arelationship between a reflectance and a reflectance difference for eachwavelength, and the acquirer acquires a reflectance difference for eachwavelength by calculation using the first spectral reflectance and therelational formula.
 3. The spectrocolorimetric device according to claim2, wherein the relationship information includes a relational formularepresenting a relationship between a reflectance and a reflectancedifference in each of a plurality of regions of reflectance for eachwavelength.
 4. The spectrocolorimetric device according to claim 1,wherein the relationship information includes a table indicating aplurality of combinations of a reflectance and a reflectance differencefor each wavelength, and the acquirer acquires a reflectance differencefor each wavelength on the basis of the first spectral reflectance andthe table.
 5. The spectrocolorimetric device according to claim 4,wherein the acquirer acquires a reflectance difference by aninterpolation process using two or more combinations of a reflectanceand a reflectance difference included in the table for each wavelength.6. The spectrocolorimetric device according to claim 1, wherein therelationship is set on the basis of spectral reflectances acquired bymeasurement using the spectrocolorimetric device and thedestination-of-conversion spectrocolorimetric device for each sampleamong a plurality of different samples of which reflectance is includedwithin a width of a preset predetermined value range in at least aportion of a wavelength range in a to-be-measured wavelength range. 7.The spectrocolorimetric device according to claim 6, wherein theplurality of samples include a sample of which reflectance is within awidth of the predetermined value range over the entire to-be-measuredwavelength range.
 8. The spectrocolorimetric device according to claim6, wherein the plurality of samples include a plurality of samples whichare achromatic and have different spectral reflectances.
 9. A conversionrule setting method comprising: (a) in a first spectrocolorimetricdevice and a second spectrocolorimetric device, measuring a spectralreflectance for each sample among a plurality of different samples ofwhich reflectance is included within a width of a preset predeterminedvalue range in at least a portion of a wavelength range in ato-be-measured wavelength range; (b) in an arithmetic, acquiring arelationship between a reflectance for each wavelength between aplurality of first spectral reflectances acquired by measurementrelating to the plurality of samples using the first spectrocolorimetricdevice and a plurality of second spectral reflectances which can beobtained by measurement relating to the plurality of samples using thesecond spectrocolorimetric device and a reflectance difference as adeviation component relating to the reflectance on the basis of ameasurement result in (a); and (c) in a setting part, setting aconversion rule for converting a spectral reflectance acquired bymeasurement using the first spectrocolorimetric device into a spectralreflectance that can be acquired by measurement using the secondspectrocolorimetric device on the basis of a relationship between areflectance and a reflectance difference for each wavelength acquired in(b).
 10. The spectrocolorimetric device according to claim 2, whereinthe relationship is set on the basis of spectral reflectances acquiredby measurement using the spectrocolorimetric device and thedestination-of-conversion spectrocolorimetric device for each sampleamong a plurality of different samples of which reflectance is includedwithin a width of a preset predetermined value range in at least aportion of a wavelength range in a to-be-measured wavelength range. 11.The spectrocolorimetric device according to claim 3, wherein therelationship is set on the basis of spectral reflectances acquired bymeasurement using the spectrocolorimetric device and thedestination-of-conversion spectrocolorimetric device for each sampleamong a plurality of different samples of which reflectance is includedwithin a width of a preset predetermined value range in at least aportion of a wavelength range in a to-be-measured wavelength range. 12.The spectrocolorimetric device according to claim 4, wherein therelationship is set on the basis of spectral reflectances acquired bymeasurement using the spectrocolorimetric device and thedestination-of-conversion spectrocolorimetric device for each sampleamong a plurality of different samples of which reflectance is includedwithin a width of a preset predetermined value range in at least aportion of a wavelength range in a to-be-measured wavelength range. 13.The spectrocolorimetric device according to claim 5, wherein therelationship is set on the basis of spectral reflectances acquired bymeasurement using the spectrocolorimetric device and thedestination-of-conversion spectrocolorimetric device for each sampleamong a plurality of different samples of which reflectance is includedwithin a width of a preset predetermined value range in at least aportion of a wavelength range in a to-be-measured wavelength range. 14.The spectrocolorimetric device according to claim 7, wherein theplurality of samples include a plurality of samples which are achromaticand have different spectral reflectances.